Life and Works

  • Not much is known about Lucretius' history. He was an Epicurian poet who wrote in dactylic hexameter and a pioneer in the writing of philosophical poetry in Latin. His extant work, De Rerum Natura, [i] is beautiful and unusual though he may not have put the final touch to it. Its primary topic is physics and Lucretius is known for his account of the clinamen, or the swerve, which has come to be a part of the discussion about ancient atomism and physics in general. He was born perhaps around 94 BC and died in 54 or 51 BC, but the sources of this information are not reliable. Cicero's claim that Lucretius has “flashes of genius” [ii] tells us that he wrote his poem in the first century BC. Early Christians vilified Lucretius because he was not a believer in any religion, one saying that he was driven mad by a love philter and that he died by his own hand,[iii] but later scientists and philosophers were influenced by him. [iv] Four fundamental themes of De Rerum Natura are universal causal explanation, the elimination of fear of the world through reason, free will and the soul's dissolution after death. [v] We concentrate here on universal causal explanation. Lucretius calls the material causes of things semina and primordia rerum and also materies, but he does not use the term “atom”, which would have been available to him. Semina means “seeds” and primordia rerum “the first-beginnings of things”. Materies comes from the Latin for “mother”. We will use the term primordia to signify all of these for simplicity and convenience, but know that Lucretius uses different terms and alternately phrases in order to indicate the same minuscule bits of material reality.

First Principles

Following Democritus, Leucippus and Epicurus, Lucretius asserts that being always existed and always will exist, similar to Parmenides and Empedocles. Nothing comes into being out of nothing:

No thing ever is produced from nothing by a god. (DRN, 1.150). ...for if things came to be from nothing, every kind of thing would be able to be born from all things, and nothing would require a seed. Men would be able to sprout first from the sea and the scaly stock from the earth, and birds, cattle and herds out of the sky. (DNR, 1.159-62). Naturally, where there would be no generative bodies for each, what would be able to stand as a fixed mother to things? But as it is, since each thing is created from fixed seeds, from there each thing is grown and goes out into the bounds of light where matter and the first bodies of each inhere. (DRN, 1.167-71). ...whatever is created discloses itself in its own time when fixed seeds of things have flowed together, the seasons are at hand...(DRN, 1.176-78). Since if they (roses, grain, vines) came to be from nothing, they would suddenly arise at an unfixed place and during strange parts of the year, naturally there would be no first beginnings which would be able to be shut out of a generating union at the wrong time. (DNR, 1.180-83).

Nothing is broken down into nothing and motion, conflict and force govern eternally-existing bodies:

...if anything were mortal in all its parts, each thing would perish from our eyes, suddenly snatched. For no use would exist for a force capable of arranging the separation of the parts of each and able to dissolve its bond. But now, since each thing consists of eternal seed, until an opposing force that cleaves the thing with a blow or penetrates inside through empty spaces and disunites it, nature allows the destruction of nothing to appear. (DRN, 1.217-224). Finally, the same force and cause would sweep away everything everywhere, unless they were held together by eternal matter entangled more or less in its own bond with itself. (DRN, 1.238-240).

There are “seeds” or primordia that generate [vi] the things humans see and a fixed mother that causes things. There exist only two per se entities: bodies unable to be seen [vii] and void.


...the wind...rages furiously and becomes fierce with a threatening crash.... [T]here are concealed bodies of wind which scour the sea, the lands, and finally the clouds of the sky and carry them suddenly, tossing them in a spinning wind. (DRN, 1.275-279). (W)e sense at a distance the different smells of things, but nonetheless never do we see them coming to our noses. (DRN, 1.298-99). Finally, clothes suspended on the wave-breaking shore grow wet, but spread out in the sun they dry. (DRN, 1.305-6). Thus into small parts the fluid scatters, parts eyes are in no way able to see. (DRN, 1.309-10). Indeed year upon year a ring on a finger grows slenderer beneath by wearing, the fall of trickling liquid makes a stone hollow, the iron hook of a farmer's plow diminishes unnoticed in fields and we observe the stone-spread paths now worn down by the feet of a crowd. (DRN, 1.311-16).


Nor are bodies held everywhere compressed through all nature, for there is in things a void. (DRN, 1.325-30). If void did not exist, in no manner would things be able to be moved. For the function of the body that stands out, that which is the natural role of body, to stand before and obstruct, would be present at each time for all things. Nothing then would be able to advance, since no thing would grant a beginning of retreat. (DRN, 1.335-39). If void did not exist, these things (oceans, lands, heavens)...would in no manner have been brought forth at all, since everywhere compressed matter would be inactive. (DRN, 1.343-45).

Objects possess empty space because of their void:

For if there is so much of body in a ball of wool as in a ball of lead, just so much of body is there equal to hang, since the function of body is to press everything down. But by contrast void's nature remains: to exist without weight. Thus the thing which is equal in magnitude but appears lighter...makes clear that there is more of void. Yet again the heavier thing affirms there is in it more body and that within it has much less empty space. It is thus...that this thing we seek exists, mixed with another thing, that what we call void. (DRN, 1.360-69).

Everything that seems to have existence of its own is composed of these two aspects of material reality:

Moreover that which exists always through itself either will act on something or will have obligation to be engaged by other things acting upon it, or it will exist in such a way that in it things are able to exist and to be carried. But there is no thing capable of acting or of being engaged without a body, nor again able to provide a place unless it is void and empty. Therefore besides void and bodies no third nature by itself is able to remain in the number of things that would fall under our senses at any time, nor anything anyone with calculation of mind would be able to reach. For the things which are always spoken of you will discover are joined together with these two things, or you will see their accidents. (DRN, 440-450).

There do exist inseparable or accidental properties of bodies and void, but they are joined (coniuncta) and incidental outcomes (eventa).


Whatever is nowhere able to be divided and sundered without a ruinous disintegration is a thing joined together, as weight to rocks, heat to fire, fluidity to water, tangibility to all bodies, and intangibility to void. (DRN, 1.451-54).


Slavery and poverty and wealth, freedom, war, harmony, and the rest by arrival and departure of which the nature of things remains whole, we are accustomed to call...accidents. (DRN, 1.455-58).

The minute parts of any given object are tiny and imperceptible. Science calls them atoms, but Lucretius called them primordia rerum or the indestructible primordia of things:

Furthermore, bodies are in part the primordia of things, in part those which consist in the bond of their origins. But the things which are the primordia of things no force is able to extinguish; for with dense body they at length conquer. (DRN, 1.483-86).

These first-beginnings Lucretius also calls semina or “seeds” [viii] and sometimes materies [ix] or “matter.“ These first-beginnings are uncut, everlasting, yet they posses parts that would not exist except for the combination that they are, which in turn makes the first-beginnings:

For wherever always space is vacant, what we call void, in that place no body exists; where far off body holds itself, there in no manner is empty void. Thus first bodies are dense and without void. (DRN, 1.507-10)

Then further, since there is always an outermost extremity of that body (the atom), which our senses are now unable to discern without parts, and consists in the smallest nature, and neither did it ever exist cut from itself, nor will force exist for it to be cut, since it is on its own a part of the other (body) both first and unified, and then some and other similar parts in rank fill the nature of the body (of the atom) in a condensed moving collected multitude; parts which, since they are unable to exist separately, must necessarily adhere to that from which they cannot in any manner be torn away. (DRN, 1.599-608).

In other words, the first-beginnings are themselves indestructible, but if we were able to break them apart, their constituent elements themselves would vanish. Lucretius does go on to say that these primordia rerum do not have parts:

For although fundamentally the height is infinite, nevertheless the bodies which are smallest will equally be composed of infinite parts. But since true reason cries out and denies that the mind is able to trust it, it is necessary to grant that there are finally things furnished with no parts and come from the smallest nature. (DRN, 1.620-26)

What he seems to mean is that these elements of things are the smallest of things that can have generative properties, like connections, weights, blows, concurrences and motions:

Lastly, if nature the creator of things had been accustomed to compel all things to be unbound into their smallest parts, the same nature would be completely unable to retrieve again anything out of them, since because they are composed of no parts they cannot have what generative principles must have, various bindings, weights, blows, assemblages, motions, through which each thing is produced. (DRN, 1.628-34).

The modern tendency is to call them “atoms”, but the term “atom” comes from Democritus and Leucippus, which means “uncut” or “uncuttable” as we have seen. Since what we call atoms in Lucretius' system are fundamental and unbreakable elements that themselves have parts and since they can be separated, they are not the Democritean atoms. They are similar to our atoms in that they are fundamental pieces of the universe that themselves are not the most fundamental part of material reality, [x] and in one sense these “atoms” are singular and unified ever smaller pieces and in another sense they are the fundamental, unbreakable pieces of material reality that comprise all bodies. One may make an analogy between modern atoms and sub-atomic particles that comprise them, as with Plato's reception of the Democritean atom.

Body and void exist together with these primordia as the objects we see and make up the dynamic that allows for outside and inside forces to change things:

In addition, unless matter were eternal, before now each thing would have returned absolutely to nothing, and from nothing would be born again whatever we see. But since...nothing can be brought forth from nothing and what has come about is unable to be restored to nothing, primordia must exist immortally in body into which each thing may be dissolved at its last moment, so that matter may be upcoming for the remaking of things new. (DRN, 1.540-47).

Primordia are part of the procreative matrix of the universe, yet they have their own generative nature. They are the pieces that make and the parts that are made into things from the connections, weights, blows, concurrences and motions of the universe. The universe for Lucretius is infinite, extending infinitely with what we call gravity [xi] as a fundamental force of change:

In addition, if all space in the universe together stood enclosed in fixed boundaries on all sides and were limited, by now the abundance of matter would by its dense weight have flowed together from all parts to the lowest place, nor could anything be accomplished under the cover of sky, and sky would not exist at all nor light of sun, because...all matter would have been lying already piled up from settling down through infinite past. (DRN, 1.984-91).

The universe possesses infinite matter mixed with void:

Furthermore, so that the sum of things is not able to arrange itself nature stands guard, nature who compels what is body to be bounded by void and what is void by body so that by alternates she delivers an infinite universe, or as yet one or another, if one did not bound the other, would yet simply open itself without limit. (DRN, 1. 1008-13).

Causation and Cosmology

The first-beginnings move constantly and through movement they change the things composed of them:

For since the primordia of things wander through the void, it is necessary that all be born either by their own weight or by the accidental blow of another. For when roused and having met they often collided, it comes about that having separated they leap apart suddenly; and no wonder, since they are hardest in their dense weight and nothing opposed them from behind. (DRN, 2.83-8). ...there is no lowest limit in the sum of things nor do the first bodies have place to stand, since space is without end or limit, it extends boundless from all sides in all parts, a thing shown to be demonstrated by many things and by certain reason. No wonder no rest is granted to the first bodies throughout the deep void, but rather agitated by constant and varied motions, some pressed together then leap back along wide distances, some even in small spaces are shaken by a blow. (DRN, 2.91-8).

Somewhat stable arrangements of primordia make up the objects we perceive and our own bodies:

And those heaped together in a more condensed union leap back through narrow spaces, caught fast in their own interwoven shapes, these constitute the vigorous roots of stone and the savage bodies of iron and the rest of their kind. (DRN, 2.100-04).

These arrangements are in motion, though we do not perceive it. [xii]

...since all the primordia of things are in motion, the sum seems nevertheless to stand in supreme rest, except for anything that may give motion with its particular body. For the whole nature of first things resides far beneath our senses; on account of which where you cannot see them themselves they necessarily keep their motions from your sight, especially when things that we are able to perceive do often hide their motions when separated a great distance. (DRN, 2.309-16).

The void and matter present in objects account for their density; Lucretius believed that because body and void mingle in objects, each thing has its own weight. No body can move upward unless it is affected by some force. [xiii] Bodies fall downward of their own accord, but they do not fall without a somewhat arbitrary interruption. If they did, then there would be no collision and thus no coming to be of anything. Gravity [xiv] is a fundamental causal agent in the matrix of the universe, but it cannot produce objects on its own because blows and collisions are needed to form things, as we have seen. There exists a force that deviates falling primordia from a certain and unbroken path. The force in the universe that causes this deviation Lucretius calls the clinamen, [xv] or “swerve.”:

...while the first bodies are carried down by their own weight straight through the void, altogether at uncertain times and in uncertain places, they turn aside a little from their course, just so much as you may call a changed motion of weight. For if they were not accustomed to bend aside, all would fall downwards as drops of rain through the deep void, no collision would come to be and no blow would be caused among the primordia: thus nature would have produced nothing. (DRN, 2.217-224).

All the primordia fall at the same speed through the void and so in order to create some kind of difference that begets a collision, which in turn gives things their properties, a swerve from their uniform fall to the earth becomes necessary. Thus, the clinamen.

Primordia exist in as many kinds of shape as exist in the parts of any species. Each shape has a different ability and performs a different function when they are conglomerated. [xvi] We can see how they function in ordinary experience.

...through a colander we see wine suddenly...strain; but to the contrary olive oil sluggishly hesitates, either, no wonder, because it has larger elements, or they are more hooked and folded among themselves, and for that reason it comes about that the individual primordia are unable to be so detached unexpectedly and penetrate individually through the opening of each. (DRN, 391-97).

Qualities in things come from the shape and characteristics of the primordia. Lucretius describes how the shapes of the primoridia and their possible conglomerates make the substances that we find in nature.

Again, what appears to us as hardened and close, these things must consist of elements more hooked among themselves just as if held together deeply by branch-shapes. Among the first of this kind invincible stones,...stand in the front rank, accustomed to disregard blows; and granite and the firmness of unyielding iron and bronze bars that shout while resisting the bolt. Those others, the liquids that consist of fluid body, must be comprised of elements lighter and more spherical. (DRN, 2.444-52).

The shapes of the primordia are limited in number. If they were not limited, some would be limitless in size.

Increase of body follows novelty of shape. On account of which it is not the case that you are able to believe different seeds to exist in infinite shapes, otherwise you must compel certain of them to be of immeasurable magnitude.... (DRN, 2.495-99).

The primordia of any shape are infinite in amount. Otherwise, the sum of the bodies would be finite and the manner of combination of finite primordia would not be possible.

Truly, since the difference of shapes is finite, it is necessary that what shapes are alike be infinite, or that the sum of matter be finite, the thing which I have proved not to be. With verse I will show that small bodies of matter hold the sum of things from infinity with a continuous succession of blows from all parts. (DRN, 2.525-31).

If I should assume that the bodies generative of one thing and scattered in everything were finite, from what place, where, under what force, having come together in what way will they assemble in such a sea of matter, in such a strange disorder? (DRN, 547-50).

Lucretius is talking about the generative aspect of the primordia. They are not merely inactive elements that other forces of the universe manipulate, but rather they actively participate in becoming. Nothing consists of one kind of primordia; Lucretius uses earth as an example:

There is nothing of those things in nature plainly that consists only of one kind of principle, nor anything that does not consist of various intermingled seeds; and whatever thing possesses many forces and more abilities in itself, so it shows there are within it most generative things and various shapes. First, the earth holds the first bodies in itself from which springs, turning, the cold around assiduously renew the immense sea and contains that from where fires arise. … then further, earth contains means to lift up bright fruit and joy-bringing trees for mankind, that source from which it is able to produce rivers and leafy branches and glad pasturages for the mountain-ranging stock of feral beasts. (DRN, 2.583-97)

The primordia of the earth are generative because they produce different things from themselves. They must be different, each one possessing a different ability to produce. Primordia are not all conjoinable with one another, certainly not arbitrarily. Otherwise, horrible creatures and objects would result. As different as things are from one another, so different are the primordia. Lucretius claims that such difference is necessary:

For just as all things made are completely different from each other, so it is necessary that each consist of primordia differently shaped; not that very few are endowed with a similar shape, but that commonly not all are composed equally to all. Since, further, seeds differ, there is need that intervals, paths, connections, weights, blows, assemblages, motions differ, which not only separate animal bodies, but sever the lands and the whole sea and hold back all sky from earth. (DRN, 2.720-29)

Otherwise, all of the primordia would come together in one homogeneous mass. The primordia do not have the same qualities that arise from them. They lack heat, sound, moisture and smell.

The primordia of things must not add their own smell to things in the making, nor sound, since they are capable of emitting nothing from themselves, and for a similar reason no taste at all, not coldness, nor heat besides that nor tepid vapor or the rest. … it is necessary that all these be separated from the primordia, if we wish to establish an immortal foundation for things upon which the sum of vigor may rest: or else you find all things pass back absolutely to nothing. (DRN, 2.854-64).

It would seem as if primordia are similar in function to the parts of the primordia themselves. They emit nothing and have no qualities in themselves, but when combined in certain ways they make the qualities of things in the universe. The parts of the primordia themselves cannot exist without the combinations that make them, yet the primordia themselves have their own cohesion and unity. Just so much do the primordia not have smell or taste or sense and yet combinations of them give rise to these qualities.

The universe that we know is not the only universe because of the infinite number of elements interacting. When the possibility of some cosmos to exist or thing to arise is there, there is a generation of things; innumerable primordia lead to innumerable creatures and objects. The variety and number of creatures and objects is proof of this assertion:

Now, it must not be supposed that this is the only circuit of lands and sky that have been made since limitless space lies open everywhere, and since seeds innumerable in number and the sum of depth fly about in many ways driven by eternal motion, nor that so many of those bodies of matter outside do nothing: especially since this place was made by nature, and seeds themselves by their own volition pushed and thrown together in many ways, at random, without aim, to no purpose, have cultivated those which are suddenly joined so as to become always the origins of great things... (DRN, 2.1052-62).

Because nature generates creatures and things itself there are no gods.

If you have these things thought well in mind, straightway nature is seen to be free, rid of arrogant masters, herself doing everything by herself spontaneously, and she is seen to have no part of the gods. (DRN, 2.1090-92).

We have seen that Lucretius believes the nature of things and how they act are determined by the shape and the nature of the primordia of things. He also seems to believe that shapes determine actions of larger objects; these same shapes are present as causes for qualities of objects, as we have seen.

But that which necessarily is movable must consist of seeds extremely rounded and minutest possible, that they are able to be moved when incited by little motion. For water is moved and flows with so little motion, obviously made of small circling shapes. But on the other hand the nature of honey is more cohesive, its fluids more inactive, and its impulse more delayed; for the whole abundance of its matter clings to itself more closely, no wonder because it does not consist of bodies so smooth or so fragile and round. (DRN, 3.186-95).

Once the primordia have found their proper place, they are then able to perform their function.

Finally, why are the rational mind and plans never produced in the head or feet or hands, but they cling to individual positions and fixed region for all, if not because fixed places are imparted to each thing for growing and somewhere where it is able to endure when made...? (DRN, 3.615-19). … (a) tree cannot exist in the sky, nor clouds in the deep ocean, no fish live in fields, nor blood in sticks or sap in rocks. It is a certain and set forth thing where each thing grows and inheres. (DRN, 3.784-87).

It is important to note that Lucretius uses examples of everyday growth and flourishing to support his claims. Here is an inductive element, an example that demonstrates his willingness to observe and then reason. Thus, perception is prominent in his thinking.

Lucretius trusts the senses, which always grant the truth. What is seen comes to the perceiver through simulacra, which are images flowing to the eyes and ears through the air. What is most important about Lucretius' view of senses is that they are to be trusted, even when they present illusions. [xvii] The philosopher who does not trust the senses but rather only reason is in a conundrum. The only means through which reason may develop its stance is through senses, yet some say the senses are not trustworthy. Reason would then have no foundation for itself. Lucretius asks if reason will be able to refute the senses when they are completely derived from the senses. In this manner, he infuses a strong empirical element into his system.[xviii] He praises and employs reason, but only once the senses have given it what it needs to fulfill its nature. Equal credit is to be given to each sense for what it senses. Sounds reverberate because some of the pieces of the sound fall into the ears while others bounce about on rocks and other objects. In fact, as we have seen, the whole of Lucretius' cosmos is composed of blows that come from the primordia striking one another. Senses are those parts of human being that receive these blows and later interpret them. All of the universe is in this sense material and explainable through physical interactions of material things. These interactions seem to be primary and that is why the senses must be trusted. They receive what is fundamental to the whole of the order of things. Lucretius interprets hearing and taste through this same lens and there thus arises the need to explain why we can hear sounds when there are obstructions, like walls, that ought to prevent any contact between the origin of the sound and the perception. His system is in this sense one-sided, most of his reasoning proceeding from a few insights. Perhaps these are the “flashes of genius” about which Cicero wrote.

In contrast to thinkers like Plato and Aristotle Lucretius believes the mind to be not only material but a physical interaction of a narrow kind. Everything, including the movements of the mind, is material, and how something comes about depends heavily on the shape and substance of the primordia.

...many likenesses of things are moving about in many ways and all around, thin, which easily join themselves in the air when they encounter one another, as if a web of leaf-gold. Naturally, these are much more thin in structure than those which seize the eyes and excite vision, since these things penetrate through the mesh of the body, stir the thin nature of mind within, and stimulate sense. Thus it is we see Centaurs, and the limbs of Scylla, and faces of dogs like Cerberus.... For certainly no image of a Centaur comes to be from one living, since never a living thing of this nature existed. (DRN, 4.725-739).

In this sense Lucretius anticipates the method of modern science in that for each and every topic available to him he sees a material explanation, in some cases radically simplifying the process of explanation – like the viscosity of water as opposed to honey. Lucretius seems to anticipate Darwin's theory of evolution by claiming that combinations, blows and recombining of primordia create creatures and objects until there exists a stable, survivable species.

For so many primordia of things with so many manners, from infinite time now excited and roused by blows and their own weight they have been accustomed to be carried and to assemble in all manner of ways, and to attempt all things, whatsoever they, having come together, were able to produce, that it is no wonder if they fell into such arrangements as well, and came into such courses, by what nature this sum of things now shows in the renewal of their making. (DRN, 5.185-94).

He claims that water and air and other elements of the earth perish and again are born. It is the constant rearrangement of things that provides an empirical example of how the universe is composed of bodies that come to be and perish. Becoming, then, is his main focus as evidence for a material universe:

And since the body of earth and fluid, the light currents of air, and hot steam from which this sum of things is seen to consist, all remain in a body born and mortal, the whole nature of the world one must suppose to be of the same thing....(DRN, 5.235-39). ...and since beyond doubt she is seen to be at the same time the parent of all and the common sepulcher, therefore you see that the land is lessened and once increased regrows. (DRN, 5.258-60).

He continues to provide examples of objects breaking apart and combining again into new objects. Lucretius speculates on the material causes and movements of heavenly bodies, always taking as the primary cause a material interaction, yet he asserts only suggestions in some places, like alternate explanations for the movement of the sun and the light that shines from or upon the moon. He claims that there are many possible causes for given events, and multiple causation seems to be an appropriate element of his system, since he believed that objects and creatures arose randomly as the primordia combined and dissolved only to recombine. It is this same perspective that makes him believe that there are infinite worlds. He says that creatures “by fixed law preserve the distinctions of nature.” [xix] Lucretius does not appear to question deeply what the consequences are of his insights. He promotes his assertions with examples, yes, but how there is such a fixed law of nature he does not adequately address. He ends his poem with explanations of natural phenomena, like clouds and lightening and evaporation. All of these forces he explains in material terms, insisting that reason be employed in order to learn the nature of things. He seems to believe that the laws of nature remain the same everywhere. The universe is a vast order and men are insignificantly tiny parts of it:

…for nature herself demands to be at every part like itself. (DRN, 6.542)

It must be that in these affairs deep and far you look, and distinguish all parts broadly, so that you may remember that the sum of things is vast, and you see the sky as one, a tiny and trifling part of the whole sum, not so much a part as one man is of the whole earth. (DRN, 6.647-52)

Substances adhere to one another or repulse one another depending on the amount of void in each object along with their shapes, as we have seen. He thus explains the nature of the magnet and also the reason why certain substances attract and mix while others do not. Oil does not mix with water but wine does. Tin can adhere bronze to bronze. The void in an object and the body in an object together enable the combinations of things. Each of the primordia have a different kind of productive power. It seems then that variety of primordia is responsible for varying functions and causes in the universe. Multiple causes exist as a result of this perspective and his universe seems to have as many causes as it does variety of bits of reality. Consistent with this view is the idea that there exists a finite variety of primordia but an infinite number of them.

One thing remains to examine in Lucretius' view of things. We have seen that there is an empirical element to his reasoning in his use of examples, yet there is no verification process. Lucretius speculates as to the process inherent in the example; he does not control the process and verify that the example is precisely what he claims. Also, his verification of things by no means is rigorous or sophisticated; speculation is a very powerful element of his partially empirical system. In order to place his thinking in the context of the other thinkers we have examined, an analysis of some of the above arguments is in order. We may then see how his manner of reasoning is part of a system similar to other ancient systems. These other systems have as part of their structure a scientifically logical framework and a comparison may then be made. First, we will examine his view that the universe is composed of the minuscule primordia that have a generative ability. Second, we will examine his view that void exists and that void is mixed with body. Third, we will look at one argument for the generative ability of the primordia and how Lucretius argues that these bits of reality make the objects and creatures around us. We will see that Lucretius' thinking is valid if not sound. His reasoning is not as vigorous as Plato or Aristotle nor as deep as Heraclitus or Parmenides, but it possesses a fair logical structure coupled with the empirical verification we have already seen.


First, Lecretius argues that there are minuscule pieces of material reality, alternately called primordia rerum, materies and semina. Particles of water, metal and stone wear down gradually as humans use them. These are common experiences that seem to occur regularly enough to claim universality. A modern scientific interpretation of these occurrences would claim that there is a degree of probability that, say, the metal of a ring will wear down with use. The degree of probability is high enough that we can claim a virtually universal law for all practical purposes. Thus it is with scientific discovery of material law today. Lucretius seems to believe that the laws of the interactions of material are in fact universal, largely because of their reliability. He thus makes a universal claim that seems credible, yet his assumption is that these interactions of matter will always remain the same. His logic follows the same path, though his verification comes from what ancients like Plato thought of as unstable change. He assumes that matter remains the same before he argues that it is fixed and so he implies universals:

  • All material processes too small to see because of their small size are processes involving primordia.
  • All material processes too small to see are material processes too small to see because of their small size.
  • Thus, all material processes too small to see are processes involving primordia.


  • All material processes too small to see are processes involving primordia.
  • All water gatherings on the shore are material processes too small to see.
  • Thus, all water gatherings on the shore are processes involving primordia.

One can substitute the wearing down of metal or the erosion of stone by water for the water gatherings and find the same form of argument. The material processes are likened to one another by the size of the elements involved and the wholly material relationships. The logic of the argument is sound and so Lucretius makes good his reason, yet he assumes that the processes are material only. He also seems to assume that the elements in his system are constant, a kind of eternal materialism. He has discovered something correct about the material universe without the use of implements like microscopes and mathematical speculation, but his correct assertion is qualified by speculation. There are tiny bits of material reality that constitute objects and creatures, but they do not possess the nature that he assumes. A more rigorous system of control and manipulation like we saw at the beginning of this text would demand at least more argumentation and defense of problematics that emerge. How precisely do the primordia of water depart from the clothing on the shore would be a question worthy of almost an entire book's answer. Lucretius does not concern himself with these details; remember that he lists various causes for different events.

Lucretius also asserts that void exists, as we have seen, seeming to assert that void exists in two ways. He claims that void is part of the physical matter that exists in the universe and that void provides the space for movement. Really, these are the same function of void. The proof of void in matter we look at first.

  • All weights that press down are things made lighter by a lack of body.
  • All things with body are weights that press down.
  • Thus, all things with body are things made lighter by a lack of body.
  • All things made lighter by a lack of body are things with void in them.
  • All things with body are things made lighter by a lack of body.
  • All things with body are things with void in them.

We cannot make the same conclusion as Lucretius because his premises make assumptions about the nature of material reality that he does not prove nor argue. It is not necessarily the case that things that press down are made lighter by void as much as it is that things press down because of how they are constituted. A complete void does not exist nor is it part of objects and Lucretius does not argue rigorously for a complete void, nor does he put forth convincing examples for its existence. Void and its affects are assumed in many ways; he believed that the only reason one object could be lighter than another is that it has void in it. Yet, Lucretius uses examples in order to argue his case and an element of more direct empiricism has found its way into his reasoning, as we have seen. His is not the categorization of Aristotle nor the speculation of a Parmenides or a Plato. Natural processes as they exist are a large part of Lucretius' reasoning, but he speculates on what precisely are the processes without further or repeated examination. His lack of empirical verification leads him astray as speculation mislead others before him, even though he trusts in the senses to give him efficacious examples.

Lucretius also claims that the shapes of these bits of material reality have some effect on how they act in everyday experience. More than one type of primordia exist and they combine to form things that have more than one ability. Each has its own power and thus naturally when an object is composed of more than one primordium, it has more than one power. These bits of material fall naturally to earth and the collisions that result from their knocking against one another are the motions that compose objects and creatures around us. Thus, we recall Lucretius' clinamen. He reacts to a criticism that if the primordia fall to earth they ought to fall in specific and unwavering trajectories, in which case a rigid and unalterable causation would dictate how things come to be; there would be no random [xx] element that allows for the differing direction of things and variable change. Free will would not exist as well because our minds are merely material objects like other things. The clinamen, or swerve, is the answer to the criticism. It lets Lucretius assert that no absolute trajectories dictate becoming. One form of his arguments are as follows:

  • All things held together by branch-like shapes are things accustomed to despise blows (tough things).
  • All hardened and close-set things are things held together by branch-like shapes.
  • All hardened and close-set things are things accustomed to despise blows (tough things).

Now, this argument claims that hard things are things accustomed to despise blows, which means they are tough. These tough things are all things that have as a commonality, or a category, the physical property of being held together by branch-like shapes. The shapes are then the determining factor in the toughness of the substance and so shapes are determinant in the production of physical quality. Lucretius applies shape to diamonds, iron and bronze. Iron and diamond are obviously composed of different shapes because they have different qualities, but the category of hardness comes from a similar shape. The argument is valid in that the form is good, but the premises come from a speculation that itself arose from an observation. Since Lucretius trusts observation, he proceeds no more deeply, though more observation may prove that his assertion is not as universal or correct as it seems. Lucretius argues further that no object is composed of one simple kind of element:

  • No objects that have many abilities are objects made of only one kind of element.
  • All objects in plain view are objects that have many abilities.
  • No objects in plain view are objects made of only one kind of element.

Again, Lucretius has rendered a valid argument that is not sound. The sound argument must have true premises along with good form. His argument here has merely good form, but again the empirical dimension to Lucretius' argumentation is speculative guess-work that has itself a low degree of probability. He thinks to have found an explanation of how things come about without examining more closely in order to verify his perspective. Lucretius further argues that causation arises from what we call gravity coupled with a deviation from objects' path or paths. The deviation from the path causes the collisions that themselves create the objects and creatures of the universe.

  • No results of collisions are things possible without the clinamen.
  • All existing things in the universe are results of collisions.
  • No existing things in the universe are things possible without the clinamen.

Gravity in the object, and for Lucretius density, is a fundamental force of the universe not only because it pulls objects downward but it is one aspect of causation without which collisions and thus objects themselves would not be possible. Lucretius argues his case fairly well, as we can see from his valid arguments, yet, again, he does not pursue his case rigorously. He contradicts himself when he claims that the primordia have no characteristics themselves and he also states that these fundamental bits of material reality also have shapes that produce specific characteristics. He had no sense that he ought to prove his assertions rigorously with evidence perhaps because of the tendency for influential thinkers like Plato and others to distrust experience in general; specifically were ancient thinkers distrustful of particulars. Many centuries passed before a rigorous empirical proof became a requirement for verification of scientific theory, and so Lecretius' views can have only a partial veracity to them. He came up with many insights that proved to be correct in their essence, if not precisely what he imagined. Imagination for Lucretius was an intimate part of his insight and he was able to go no further without new tools, yet he does not seem to have out-imagined himself in the way that Empedocles did. His imaginative view of the invisible primordia did not run amok so much as it reached beyond the grasp of his senses.

  • [i] De Rerum Natura is sometimes seen as an epic (Donahue). Lucretius seems to want to change the reader's mind (See, Solomon, Gale, Volk).
  • [ii] Cicero, Letters to his Brother Quintus CXLVII (Q, FR III, 1).
  • [iii] St. Jerome.
  • [iv] De Rerum Natura influenced such notables as Newton, Dalton, Maxwell and Kelvin. For more on the influence of Lucretius on science, see Downs, Fisher. Kenneth Rexroth talks about the correctness of Lucretius view, saying “no sounder view of nature was to appear for almost two thousand years. We should understand that the atom of Lucretius is not our atom, much less our molecule, it is the foundation of our physics of ultimate particles.” Gassendi (See Fisher, 191) follows the ideas of Lucretius most closely.
  • [v] Some scholars believe that Lucretius' main aim is to eliminate fear; the seemingly cavalier attitudes Epicureans take toward discovering precise causes is one possible piece of evidence for this stance. For more on this interpretation, see Mayer, Wasserstein. Diogenes Laertius (DL, X, 79) expressly disagrees with Lucretius, saying that there is nothing in knowledge of eclipses, solstices or risings or settings that makes human beings happy. The Epicurean perspective was far from universal, and it is important to note that the seeking after causation was not rigorous for the Epicureans. They may have been more concerned with the affects of a reasoned life than with reasoned argumentation.
  • [vi] Lucretius seems to have interpreted nature as in itself powerful, in itself without a master, like a god. There is a random element to that ability, but it is sometimes viewed as both random and necessitated. Monte Ransome Johnson calls this element an ability of nature “as a proposition in natural science, the result is that nature of its own accord behaves in a way that it would otherwise be compelled to do by law” (Johnson, 105). The behavior of nature for Johnson then is something that possesses “law-like regularities”, which means that the same patterns of nature science seeks are the patterns of universals. Lucretius gives a kind of antidote to the metaphysical and spiritual speculations of a Plato or an Anaximander (See Kevorkian). For more, see Johnson, Fowler. For a different perspective, see Long.
  • [vii] These speculations are based upon observation, an inductive method. Lucretius employs observation in a serious manner, and that is one scientific aspect of his thought. Still, he lacked rigor and the control methods that he desperately needed.
  • [viii] De Rerum Natura, 1.500-2.
  • [ix] De Rerum Natura, 1.56-60.
  • [x] W.T.L. talks about how Lucretian atoms themselves have parts, or minima of the material world. It is the perspective of this text that Lucretian atoms are not technically uncuttable. For more on how atoms have parts and yet are not separable, see W.T.L. For a clear and basic comparison of the ancient and modern atom, see Stocker.
  • [xi] Lesage notes how likely it is that if the Epicureans had possessed geometric knowledge and some cosmographical knowledge of the day, they would have discovered the law of gravitation and its cause. Ritchie points out that Lucretius shows no signs of scientific knowledge of the ancient world. Lucretius' induction and empiricism is quite strange, if he bases it on no contemporary theory or method.
  • [xii] C.B. Believes that should Lucretian atoms exist large enough to see, they would be unseen regardless because they do not possess qualities. Here is another strange and problematic aspect of Lucretian atomism. For more, see C.B.
  • [xiii] De Rerum Natura 2.184-213.
  • [xiv] It is important to note that ancients had no conception of gravity in the sense that we do, yet they knew that rocks fall from heights and that leaping cats ultimately come down. Saying that ancient peoples had no notion of gravity is false, but saying that they understood gravity in a scientific and thus sophisticated way is also false. The point is that even a dog understands some aspect of gravity. The ancients knew many practical things about this force of the universe and thus had an understanding of it.
  • [xv] The clinamen is a contentious issue with scholars. Some explain the swerve in terms of motion and deflection, or simply motion; some claim that it is a random element incorporated into Lucretius' philosophy in order to solve certain problems and thus it recalls modern physics; others claim that the notion of the atom has always had in it a deviation. There is some debate as to the direction and inclination of the swerve. Cicero mocks the clinamen and St. Augutine calls it “the soul of the atom”. Epicurus is said (Pullman) to have thought up the clinamen in order to answer problems that arose because of the generative force of gravity (an iron-like grip on causation would result if all falling objects fell in straight lines). Lucretius is said (Pullman) to have contributed little besides a reworking of Epicureanism and so did not think it up. One of the most significant problems for ancient thinkers concerning gravity's affect on human culture was that it seemed to destroy free will and thus morality and ethics along with it (Cicero, St. Augustine among others). Englert asserts that swerves follow volitions. Sedley claims that swerves are caused by volitions from the top down; volitions are emergent properties able to obtain leverage on atoms. It seems that Epicurus thought of atoms in three ways: weight, the clinamen and collisions. Lucretius follows Epicurus and adds little. It was perhaps a reaction to Aristotle that brought about the clinamen (see O'Keefe). Wasserstein claims that the problem of the clinamen is of ethical origin moreso than physical. It is the result of needing a problem, and so the problem is contrived. For more on its interpretation and thus function, see Clark, Winspear, Masson, Purinton, Bailey, Fowler, Englert, Pullman, Furley, Johnson, Wasserstein. For a thorough analysis, see Greenblatt.
  • [xvi] For more on the properties of atoms that produce specific qualities, see Winspear.
  • [xvii] Reason and the senses seem to be inextricably linked for Lucretius. Humans ought to trust their senses, he claims, but he also states that reason must assist in the assessment of what is perceived. For more on the relationship between the senses and reason, see Clark, Lehoux, Sharrock. Lehoux talks especially about the relationship between reason and sense perception. We may take Lucretius' view as scientific in the sense that perception is absolutely needed but that a strong element of reasoning must accompany our senses, perhaps a precursor to objective analysis. The inability of the senses to give certain truth may be the result of atoms being counter-intuitive: they have no color, smell, temperature and they are thus difficult to pinpoint perceptibly. For more on images involving perception, see Dyson.
  • [xviii] Some scholars believe that Lucretius posited a “theory of radical induction” based upon observations that in turn were combined with reason in order to discover a truth about nature. Lucretius is supposed to have anticipated Bacon's Novum Organon by many centuries. Perhaps “radical induction” is overstated, but one can at least rest assured that Lucretius' manner of reasoning possessed a strong empirical and thus inductive element. Alban Winspear remarks that “it was only in dealing with small and circumscribed problems, where an idea could be brought immediately to the test of practice, that the ancient man of science can be said to have developed a scientific method.” p. 84. Crew claims that there were two methods for the ancients: philosophical and mathematical. Galileo made a third: experimental. Vavilov asserts that “the poem of Lucretius is the first attempt preserved to explain nature completely on the basis of physical principles.” p. 24. For more, see Winspear, Stocker.
  • [xix] De Rerum Natura 5.922-25.
  • [xx] Lucretius inserts in his physics a strong element of randomness, which was antithetical to most ancient thinking. For more on randomness in Lucretius' work, see Clark.


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