The Stanford Encyclopedia of Philosophys entry on Lucretius has:

"First comes, in effect, Lucretius' ontology. Nothing comes into being out of nothing or perishes into nothing. The only two per se entities are body and void; all other existing things are inseparable or accidental properties of these (Lucretius' own terms for which are conjuncta and eventa respectively...Lucretius next turns to the basic truths of physics. Body comes in minute and physically indivisible portions, atoms".

Before Einstein came along Energy & Matter were separate 'substances' in Physics. (I use the word 'substance' guardedly here as I understand the term has its own history in Philosophy, and I'm not au fait with the literature to qualify it correctly here). However Lucretius claims that there is only one substance 'body' in the quote above. This would mean, I claim, that in his ontology the separate substances of matter & energy are illusory and should be subsumed to an underlying substance of 'body', and since his 'body' is atomic this would require that energy is atomic too - ie the quanta of planck.

Further since his atoms are by definition indivisible, that they cannot vanish, and there are only a large but finite number of them we also have the conservation principle of mass/energy.

Is this argument valid? And has it been made in the literature?

  • Just in passing, you may be interested in The Birth of Physics by Michel Serres, which discusses Lucretius in depth, and with consideration of other thinkers of his era; I might suggest it as providing a thoughtful consideration of his thinking and legacy. (I might suggest it be read as a secondary text, perhaps after working through De Rerum Natura, but it stands on its own and you needn't have read any Lucretius yet to enjoy it.)
    – Joseph Weissman
    Nov 7, 2011 at 0:25
  • I had a professor (who was a mathematician and had a relatively famous article published on quantum mechanics), who once said that if someone from the future were to go back in time (to whenever really) with a "complete book of physics" (which we are very far from having nowadays), it would be completely meaningless. (That is, until human beings came to the same conclusions, in which case it would be superfluous.)
    – Jon
    Nov 8, 2011 at 20:45

2 Answers 2


Conservation of matter: yes.

Atoms cannot perish, and they have probably always been; Epicurus and hence Lucretius argue that the universe must always have existed, since otherwise it would have emerged out of nothing, which is to them impossible. Whenever an object is destroyed, its atoms must go somewhere; and, whenever an object is created, its atoms must come from somewhere.

Similar views had been quite popular among Greek natural philosophers. Heraclitus (c. 535 – c. 475 BC) before them said it like this:

πάντα χωρεῖ καὶ οὐδὲν μένει” καὶ "δὶς ἐς τὸν αὐτὸν ποταμὸν οὐκ ἂν ἐμβαίης"

"Everything changes and nothing remains still... and... you cannot step twice into the same stream" — (Wikipedia)

By this he meant that a stream is never the same because it consists of different bits of water each moment. Democritus (ca. 460 BC – ca. 370 BC) probably inspired Epicurus a great deal with his atomism, which includes indestructible atoms that cannot be created or destroyed but have always been. Both Democritus and Epicurus/Lucretius held that there were different kinds of atoms with different shapes, which affected the properties of the objects composed of these atoms.

Conservation of energy: probably not.

Lucretius did not really have a concept of energy as in modern physics. Heat consisted of some kind of fire atoms, so that would probably fall under conservation of energy; but others kinds of energy, like potential energy, probably did not—or, rather, it would be better to say that he never expressed an opinion about it.

The soul, which is destroyed upon the death of the body, consists of air atoms and guides the body with air. This too was a popular concept in Antiquity: ghosts, phantoms, life force, etc. are often said to be related to air and wind. Latin spiritus ("spirit, breath") comes from spiro, "to blow", as in divine breath. Animal "animal", anima "life force", and animus "mind, emotions" all come from a stem that means "breath, wind" (cf. Greek ἄνεμος /anemos/, "wind"). So perhaps the combination of air and fire atoms could be considered a semi-equivalent of energy; but there are still many other forms of energy that he simply did not consider as such, nor could air be converted into fire.

If one reads the whole De Rerum Natura, the impression one gets is that Lucretius simply did not concern himself with the question of energy in the modern sense. He just assumed that atoms could move for various reasons, without mentioning energy as a separate factor.

However, I have no doubt that he would have eagerly accepted the modern concept of conservation of energy once explained to him, because it would fit his other theories remarkably well.

I don't know Heraclitus very well; we do not have a great deal left of his writings; and his style is rather enigmatic: however, he believed that the entire universe was somehow based on fire. It was the basic element of everything; it caused all the other elements to be. If you compare this to the the modern law of the conservation of energy and the equivalence of mass and energy, perhaps he was not too far off. But it is very hard to interpret how Heraclitus intended this primacy of fire; perhaps it is quite different.

  • If lucretius described heat as atomic then that fits in with what I'm trying to get at. Had he known of potential energy I assume he would have said there were potential energy atoms. However I hadn't clearly understood that he thought atoms had different shapes - I had imagined it was the different shapes that a number of them made which was important.But looking at the SEP again: Epicurus had attached enormous importance to the internal structure of atoms, which he held to consist of altogether partless magnitudes called ‘minima’. Lucretius condenses and largely edits out this doctrine. Nov 7, 2011 at 5:18
  • I'm curious as to whether these 'minima' of epicurus had shape. If so, they just seem to replicate the idea of atoms at a lower level which seems somewhat redundant. If they do not, then it is the shape they create by their positions that determines the shape of the atom. I understand we do not have much of epicuruses writings - so probably this point can't be checked. Nov 7, 2011 at 5:35
  • @Cerberus, the most interesting account of Heraclitus I've ever read was McEvilley's "The Shape of Ancient Thought". He's an art historian, so take that as a word of caution. But in reading his history book, one gets the sense of inheritance H. owes to Yajnavalkya, an Indian critic who wrote commentaries on the Vedas. Can't remember if his fire was treated specifically there, though.
    – user678
    Nov 7, 2011 at 20:09
  • @bwkaplan: thanks for bringing up McEvilleys book. It looks fascinating. Does he mention in what way H owes a debt to Yajnavalkya? Mar 7, 2012 at 23:35
  • @MoziburUllah: he's able to make a case by comparing excerpts from the works of each. Even though the two men had different agendas, they used a lot of the same concepts. Too many to name. But the book is searchable on google books and the portion titled "Heraclitean Monism and Indian Thought" on p.36 can be read in its entirety. Enjoy!
    – user678
    Mar 12, 2012 at 19:49

For Lucretius, the universe is infinite, and contains an infinite number of atoms.

I don't recall Lucretius making any comments which would indicate that energy is necessarily atomic or quantized.

In short: it's a mistake to view Lucretius as an Einsteinian physicist avant la lettre.

As an aside, Stephen Greenblatt, the historian and Shakespearean scholar, has a new book out on Lucretius, which is getting excellent reviews. I've not (yet) read it myself.

  • +1; the Greenblatt looks excellent. I certainly agree we should not over-historicize the 'physics' of Lucretius -- but there may be something to what OP is getting at here: 'nothing comes from nothing' certainly reads like a conservation principle of some kind to me; of course not as formal as something like "the total amount of energy in an isolated system remains constant over time" but perhaps Lucretius, in presenting a demythologized account of becoming, could maybe be read as supplying the 'fundaments' of a rationalist physics in which a more rigorous formulation could be effective?
    – Joseph Weissman
    Nov 7, 2011 at 0:12
  • That Lucretius thought the universe is infinite in extent doesn't affect the argument I'm making. That there are an infinite number of atoms poses more of a problem. What I'm aiming at is that Lucretius would have agreed that the total number of atoms remains constant since they can neither come out of nothing nor vanish into nothing. Nov 7, 2011 at 5:06
  • @MoziburUllah: The standard reading of Lucretius is that he proposed an infinite number of atoms, but I'm not familiar enough with the literature to know if there are contrary readings out there. In terms of energy, there is nothing that I know of that would indicate that energy is limited in any form, or that it is quantized in any way. Lucretius did not seem terribly interested in describing a closed system. Nov 7, 2011 at 14:25

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