BMCR 2003.07.28

Lucretius on Atomic Motion. A Commentary on De Rerum Natura, Book Two, Lines 1-332

, , , Lucretius on atomic motion : a commentary on De rerum natura, book two, lines 1-332. Oxford: Oxford University Press, 2002. xv, 513 pages ; 23 cm. ISBN 0199243581. $110.00.

Don Fowler’s death in 1999 at the age of 46 was a great loss to the study of ancient poetry and philosophy, as we are reminded by this posthumous publication of a revised version of his 1984 Oxford doctoral thesis on Lucretius. Fowler was perhaps best known for his “postmodern” readings of Latin literature, many of which were collected in his Roman Constructions published in 2000.1 In the present work Fowler demonstrates his impressive, wide-ranging skills as a philologist, literary critic, and interpreter of ancient philosophy. This is a superb edition of Lucretius De Rerum Natura 2.1-332 and of great value to all Lucretius scholars.

As the title of the edition indicates, Fowler’s commentary covers the section of the De Rerum Natura in which Lucretius discusses the motions of atoms and explains Epicurus’ three types of atomic motion: downward motion caused by the weight of the atoms, motion in all directions caused by collisions of atoms, and the “swerve” ( clinamen) of atoms, a random motion of the atoms in a minimum of space. The only major commentary in English on this section of the poem had been the corresponding section of Cyril Bailey’s 1947 three-volume translation and commentary,2 which had become dated because of the large quantity of subsequent work on Epicurean philosophy. Fowler’s edition fills this gap admirably. The edition contains Bailey’s text of 2.1-322 along with a list of Fowler’s alterations, an introduction to the structure and major themes of Book 2, shorter introductions to each of the major sections of the text, and detailed commentary on individual words and phrases. Although Fowler’s original doctoral thesis could take account only of scholarship before 1984, this edition has been brought up to date by Peta Fowler. She has replaced some passages from ancient texts that Don Fowler discussed with passages from newer editions, included more recent bibliography, and inserted additional notes by Don Fowler. Finally, she has included as appendices three papers by Don Fowler, two of which (“Lucretius on the Clinamen and ‘Free Will’ (2.251-293)” and “The Feminine Principal: Gender in the De Rerum Natura“) appeared previously, and one, a talk given in 1993, which had not (“What Sort of Reductionist was Epicurus? The Case of the Swerve”).

It would be hard to imagine a better commentary on this section of Lucretius’ poem. Fowler is an informed and intelligent guide to all levels of the text: the choice and use of individual words and phrases, how passages in this section of Book 2 relate to passages and themes in the rest of the De Rerum Natura, the poetic task facing Lucretius, and the philosophical context in which Lucretius was writing. The commentary maintains a nearly perfect balance between attention to philological detail that is essential for a deep understanding of the poem and the larger poetic and philosophic issues at stake. An example of this balance is found in the entry that Fowler writes about a key Lucretian term, summa. In his comments on summa (154-156), Fowler correctly notes that Lucretius uses the term in several senses, often sliding between summa as “the sum of things” in this world and summa as the “sum of things” = “the universe as a whole.” Fowler then argues that this slide in sense has a didactic purpose, as Lucretius leads us from the comforting thought at the beginning of Book 2 that life goes on as material is recycled in our world, to the end of Book 2, where “this consolation is removed, and we have to see that only the summa summarum as τὸ πᾶν, the whole infinite universe, is really immortal” (155). The commentary is full of insights like this, as Fowler shows us how carefully Lucretius chose his words and to what effect he used them.

Only two things would have made the commentary more useful. First, although the section of Book 2 that Fowler comments on is a self-contained unit, it would have been even better if the commentary had covered all of Book 2 so we would be able to benefit more fully from Fowler’s learning. Second, the commentary, while well set up for scholars, will not be as accessible to undergraduates taking courses in advanced Latin or ancient philosophy. Most passages in Latin and Greek, and remarks of scholars quoted in German, French, and Italian are not translated, and this means that the sense is often obscured for readers restricted to English and Latin.

For the remainder of the review, I want to explore three issues treated by the commentary that have been at the heart of recent discussions of Lucretius and Epicurean philosophy: the swerve of atoms, Epicurean reductionism, and the nature of Lucretius’ Epicureanism. Fowler has much to contribute to the discussion of each of these issues.

Since antiquity the doctrine of the random swerve of atoms has been one of the most controversial aspects of Epicureanism. According to Lucretius (2.216-293) the random swerve of atoms as they move through space insured (1) that all atoms do not fall straight down in space but instead collide and create compound bodies and the visible world around us, and (2) that “free will” ( libera voluntas) exists. This second point, about how the swerve is meant to preserve libera voluntas, has been the subject of continuing controversy. The most recent round of debates about the swerve was touched off by David Furley,3 who in 1967 challenged the orthodoxy promoted by among others Giussani and Bailey that the swerve of atoms was meant to preserve “free will” ( libera voluntas) by being involved in every act of free choice. Since Furley’s study, a flood of articles and books have attempted to unpack the swerve, and explain in what way Epicurus attempted to preserve libera voluntas with it.4 The range of interpretations that have been proposed is wide, and makes one despair that, short of the discovery of a new papyrus fragment from Epicurus’ On Nature dealing directly with the swerve, a common consensus will be reached. The major division is between interpreters who believe the swerve is involved in every human choice or action, and those who believe it is not but preserves human freedom in other ways.5 Within the first group of interpreters there is wide disagreement about the role the swerve plays in human action. The view that is perhaps most prevalent, enunciated by Giussani and Bailey, and defended more recently by Asmis and Purinton,6 is that the swerve is involved in every act of free choice. A person’s choice to perform or not perform an action is correlated, at the atomic level, with a swerve of the person’s mind atoms. I have argued an alternate view that sees the swerve as being involved in every voluntary action of humans and animals not as the basis for free choice but as the “source of motion” that enables living creatures to initiate movement from within.7 Fowler’s view, argued for both in the commentary (301-366) and in his 1983 paper “Lucretius on the Clinamen and ‘Free Will’ (2.251-293)” (reprinted as Appendix A in the present volume), is that the swerve is the physical source of the mind’s ability to focus on mental images. This faculty, which Epicurus called ἐπιβωλὴ τῆς διανοίας, allows the mind to focus on one image out of all the almost infinite mental images available to the mind at any time. According to Fowler, the swerve of a mind atom, in combination with the living creature’s character, explains how the creature is freely able to focus on certain images that he/she then proceeds to act on. This self-initiated focusing, Fowler argues, occurs when mind atoms of the fourth “unnamed” type swerve and allow the living creature to act freely.

There are many plausible aspects to Fowler’s account of the swerve. I agree with his view that the swerve is involved in every voluntary action of human beings and animals, as the Lucretius passage at 2.216-293 seems to indicate with its use of horses at the starting gate to illustrate the swerve in action. I also agree with his view that the swerve may have a role to play in the mind’s focusing on incoming images. What Fowler does not show conclusively, though, is that the swerve is imagined to play the crucial role of guaranteeing libera voluntas at 2.216-293 in its role as the physical basis of ἐπιβωλὴ τῆς διανοίας. There are similar problems with other theories of the swerve, though, and so many scholars have tried to propose their own, different views of how the swerve preserves libera voluntas that perhaps the most attractive answer remaining is something like “all of the above.” In other words, it is possible that no modern consensus on the swerve has been reached because the swerve plays various roles in the Epicurean analysis of mental activities, all of which help humans and animals freely initiate their own actions and prevent them from being caught up in infinite causal chains. It may be that all who have published on the swerve, both those like Fowler who see the swerve playing a role in individual actions and decisions and those who see it playing a role in character development, are correct. Once the swerve was “discovered,” Epicurus and his followers may have used the swerve to explain various mental functions and characteristics, including how the mind focuses, how it moves the body when it wishes, how it decides on different courses of action, and how the more or less stable arrangements of our soul atoms that help determine our character are able to change over time. Such a broadly inclusive account of the swerve might help to explain why different ancient accounts of the swerve in Lucretius, Cicero, Philodemus, Plutarch, Plotinus, and elsewhere describe the swerve in slightly different ways.

Another controversy in Epicurean studies that Fowler comments on is the issue of Epicurean notions of reductionism and emergence. First raised in a pointed way by David Sedley in two articles,8 the issue of Epicurean reductionism concerns the extent to which Epicurus thought that all phenomena in the physical world could be reduced to explanations on the atomic level or alternatively the extent to which phenomena in the physical world were the result of “emergence,” i.e., were properties that could not be directly reducible to the atomic level. Sedley argued that Epicurus held an emergent view, and Fowler, both in the commentary and in a conference paper included as Appendix B (“What Sort of Reductionist was Epicurus? The Case of the Swerve”), argues against this. Fowler’s account is a subtly presented and well argued. Distinguishing between different sorts of reductionism, Fowler argues that Epicurus would have assented to some form of token-identity theory (roughly, the belief that all mental events can be identified with physical events), and probably would have embraced (439) “some form of type identity or reductionism.” Although the issue is far from settled, I agree with Fowler’s view that Epicurus believed that all aspects of his system must ultimately be explainable in terms of atoms and the void and left little room for emergence in his account.

At the end of this same paper included as Appendix B, Fowler hits on a third important topic: the nature of Lucretius’ Epicureanism. Here and elsewhere9 Fowler paints the picture of a “postmodern” Lucretius who argues for the single, comprehensive master narrative of his philosophical hero Epicurus and who also by the various poetic means he uses to present the message of Epicurus shows alternate ways of looking at the world. “But reading the De rerum natura is an experience of great complexity, which constantly suggests new ways of looking at the world and new stories to tell. In that sense, it is as deeply un-Epicurean as it is deeply Epicurean.” (443). Fowler here presents a view that, while it does not resurrect what he calls the “bad old days of l’anti-Lucrèce chez Lucrèce” (442), does present Lucretius’ vision of the world as a broader one than Epicurus’, one that could not quite settle on the single monolithic view of the universe demanded by Epicureanism. Fowler’s portrait of Lucretius is a provocative one and tries to capture the tension between Lucretius’ poetic and philosophic goals. Was Lucretius a poet who saw too many ways of looking at the world to be able to subordinate them to the single truth of Epicurus, as Fowler suggests, or was he a poet who was availing himself of every means possible to lead the reader to Epicureanism? More work on Lucretius needs to be done before we can answer the question.

No matter what one’s view of Lucretius is, though, one will find much to thank Don Fowler for in this magnificent commentary. It will be essential reading for all scholars working their way through this section of Lucretius’ poem. It will encourage literary scholars to pay more attention to the philosophical nuances of Epicureanism and philosophically minded readers to be more sensitive to the poetic features of Lucretius’ masterpiece.


1. Fowler, Don. Roman Constructions: Readings in Postmodern Latin. Oxford, 2000.

2. Bailey, Cyril. Titi Lucreti Cari De Rerum Natura Libri Sex. Three volumes. Oxford, 1947.

3. Furley, D. Two Studies in the Greek Atomists. Princeton, 1967.

4. For a recent bibliography see Susanne Bobzien, “Did Epicurus Discover the Free Will Problem?” Oxford Studies in Ancient Philosophy 19 (2000) 287-337, especially footnote 3.

5. Bobzien’s article (above note 4) is the most recent to argue that the swerve does not preserve libera voluntas by being involved in every human action or decision.

6. Asmis, E. The Epicurean Theory of Free Will and its Origins in Aristotle (Yale Dissertation, 1970) and “Free Action and the Swerve: Review of Walter G. Englert, Epicurus on the Swerve and Voluntary Action,” in Oxford Studies in Ancient Philosophy 8 (1990) 275-291; Purinton, J. “Epicurus on ‘Free Volition’ and the Atomic Swerve, ” Phronesis 44 (1999) 253-299.

7. Englert, W. Epicurus on the Swerve and Voluntary Action, Atlanta, 1987.

8. Sedley, D. “Epicurus’ Refutation of Determinism, ” in Συζήτησις : Studi sull’epicureismo greco e romano offerti a M. Gigante, Naples, 1983, 11-51, and “Epicurean Anti-Reductionism” in J. Barnes and M. Mignucci, Matter and Metaphysics, Oxford, 1988, 297-327.

9. Peta Fowler and Don Fowler. “Lucretius, ” in The Oxford Classical Dictionary, Third Edition, Oxford, 1996, 888-890, and “Philosophy and Literature in Lucretian Intertextuality ” in Don Fowler, Roman Constructions: Readings in Postmodern Latin, Oxford, 2000, 138-155.