Bryn Mawr Classical Review

Bryn Mawr Classical Review 2002.09.23

Richard McKirahan (trans.), Simplicius, On Aristotle's "Physics 8.6-10".   Ithaca:  Cornell University Press, 2001.  Pp. 247.  ISBN 0-8014-3787-3.  $65.00.  

Reviewed by Peter Lautner, Hungarian Academy of Sciences (
Word count: 1323 words

Simplicius' commentary is perhaps the most informative text ever written on Aristotle's Physics. It contains substantial testimonies of earlier commentaries now lost, especially those of Eudemus, Alexander of Aphrodisias, Porphyry and Simplicius' own teacher at Alexandria, Ammonius. The portion of the commentary translated in this volume deals with Aristotle's proofs for an unmoved mover who causes a single, continuous and eternal motion. The proofs were much disputed among Alexandrian Neoplatonists in the late 5th and early 6th centuries. Small wonder, then, that Simplicius devotes a long section (1326.38-1336.34) to criticizing John Philoponus' views on Aristotle's argument that no infinite capacity can reside in a finite body.1 As Philoponus' work, possibly a short piece on the subject That each body is finite and possesses finite capacity, has not survived, this passage is the only source for his criticism of Aristotle's notion.2

On the whole, Simplicius defends Aristotle's position. In chapter 6 he aims to show that there is an unmoved mover initiating a continuous and eternal motion. Aristotle's arguments are supplemented to meet later objections. Aristotle's argument for the eternal unmoved mover rests on the existence of continuous eternal motion, but he does not prove that such motion can exist. All that he says is that there must be a motion prior to any motion we posited to be the first, just as there must be a motion that follows any motion we posited to be the last. That line of thought proves only that motion is consecutive, not that it is continuous. Simplicius argues (1255.34-1256.30) that Aristotle demonstrates that the succession of motions in sublunary things is inexhaustible. The property of being inexhaustible must be derived from something continuous, however. If the motions of the heavens were not continuous and eternal, the consecutive motions of sublunary things would not be inexhaustible and eternal. Thus we can reach the notion of a single, continuous and eternal motion. In chapter 7 Simplicius examines the arguments for the primary status of locomotion among all kinds of change. He makes some corrections and elucidates some points that Aristotle left obscure. To mention but one example, at 1274.33-1275.4 he provides an explanation of Aristotle's most unclear claim (261b1-2) that 'a thing that is not always undergoing a particular motion, but that existed previously, must previously have been at rest'. He applies it to the problem of the motion that arises from contrary motions. If that motion is not one, the contrary motions must be interrupted by a state of rest. If what is becoming white were to be becoming black without having been at rest, it would simultaneously be becoming white and black. Chapter 8 establishes that circular locomotion is the only kind of motion that can be single, eternal and continuous. Simplicius discusses Aristotle's claim that the instant of change is the last instant of the process and does not belong to the interval in which the thing is in the state resulting from the change (1296.18-35). He approves of the interpretation put forward by Alexander of Aphrodisias to solve a puzzle. Socrates dies neither in the interval in which he was dying nor in that in which was dead. In fact, his death took place not in a time interval, but at the end of the time interval in which he was dying. Thus Socrates did not die in a time interval, but at the end of the time interval in which he was living. The same strategy serves to show that propositions like 'If Dion is alive, Dion will be alive' do not change truth value at all, despite the claim made by some Stoics (1299.36-1300.30).3 In chapter 9 we find the proof that circular motion is the primary kind of motion and it is the measure of other motions. Simplicius examines Aristotle's thesis (265b12-13) that things in rectilinear motion undergo locomotion non-uniformly (1317.18-1318.7). Their motion at the beginning is faster or slower than the one close to the end.

Chapter 10 carries the main thrust of the argument for the existence of an unmoved mover. Aristotle argues that that mover has no parts and hence it is indivisible. It causes the eternal and continuous revolution of the heavens. We can also find a discussion of projectile motion, an issue that became central in the dispute about kinematics and dynamics in late antiquity. Simplicius severely criticizes John Philoponus, a Christian Neoplatonist from Alexandria (1326.38-1336.34). Aristotle claims that the unmoved mover is not a spatially extended entity.4 He argues that the cause of an infinitely long motion cannot be finite. Thus the cause of the eternal motion of the heavens will not be a spatially extended entity. Of course, it needs the tacit premise that nothing can extend over an infinite space (Phys. III 5). The thesis was attacked by John Philoponus. His counter-arguments were more complex than that referred to in Simplicius' commentary. Simplicius ascribes to him only the view that the world lacks infinite power and is therefore perishable.5 Thus he can reject it by saying that, while a finite body cannot have infinite power all at once together, it can be in motion for an infinitely long time. It is exactly this sense of infinity that is required in order for the world to be eternal. He also dissents from his Alexandrian contemporary in explaining the motion of projectiles (1346.29-1348.5). Aristotle's view is that the air receives the power to move the body from the thrower. As is well known, Philoponus ridiculed this view and replaced it with a doctrine of implanted force. The thrower implants in the projectile the power to move. Simplicius takes a different view. He thinks the reason why the thrower makes the air the mover is that, due to its earthy nature, the projectile is not capable of moving upwards or laterally. This is a whose value he himself doubted. In another matter, however, he comes close to the Alexandrian interpretation. Aristotle's unmoved mover was reinterpreted by Ammonius, Simplicius' teacher, as being not only the final cause of the universe, but its efficient cause as well. Ammonius may have proposed this in order to be in conformity with the Christian notion of Creator. His interpretation was accepted by both Philoponus and Simplicius, though clearly for different reasons. Philoponus was a Christian. By contrast, Simplicius belonged to the Athenian school where Christianity was criticized and somewhat despised, but he accepted Ammonius' interpretation (1360.24-1363.24) because he could connect it to Plato's Demiurge who is also an efficient cause of the universe.

McKirahan's translation is reliable and reads well. He also used the opportunity to check Diel's readings against the authoritative manuscript (Marciana 226). The corrections are listed on pp.10-11. I have only one small query. In 1259.24-25 I do not think we need 'animals' in the translation. The Greek text does not indicate it either. The text is about the natural motion of all kinds of bodies. It may also be of some interest to compare McKirahan's translation with the one by Christian Wildberg, published in the same series. The notes are helpful and informative, though sometimes too laconic. Just one example: In note 586 (p. 179), referring to Simplicius' discussion of Ammonius' interpretation of Aristotle's unmoved mover, we are told, rightly, that Ammonius' work has not survived. But it might have been useful to refer the reader to the testimonies, e.g., in Asclepius' in Metaph. 28.31-2, 108.23-5, 151.24-7; Simplicius' in DC 271.13-21. It has already been noted that there are some problems about the compatibility of the accounts given by Simplicius and Asclepius.

The volume contains good indices and a list of discrepancies between Simplicius' text of the Physics and the text as given in Ross' edition. We have to realize that Ross' references to Simplicius' text were not always accurate. In sum, McKirahan has done an excellent job. His translation is an excellent starting point to investigate the work of one of the best commentators on Aristotle's Physics.


1.   The passage has been published in another volume of the same series, see Place, Void and Eternity. Philoponus: Corollaries on Place and Void. translated by David Furley, with Simplicius: Against Philoponus on the Eternity of the World. translated by Christian Wildberg. London/Ithaca, NY: Duckworth/Cornell UP, 1991.
2.   Of course, Simplicius could refer to other works as well, such as the De contingentia mundi or De aeternitate mundi contra Aristotelem, see Wildberg, op. cit. 100.
3.   For the fragment, see K. Hülser, Die Fragmente zur Dialektik der Stoiker. Stuttgart/Bad Cannstatt: frommann-holzboog, 1987, vol. 3, p. 1317.
4.   Philoponus' argument has been analyzed by R. Sorabji, Matter, Space & Motion. Theories in Antiquities and their Sequel. London: Duckworth, 1988, chapter 15. For a survey of this type of argument, see C. Steel, '"Omnis corporis potentia est finita." L' interprétation d' un principe aristotélicien: de Proclus à S. Thomas', in J. P. Beckmann, L. Honnefelder, G. Schrimpf & G. Wieland (eds.), Philosophie im Mittelalter. Hamburg: Meiner, 1987, 213-224.
5.   The whole argument has been preserved in an Arabic summary, see S. Pines, 'An Arabic summary of a lost work of John Philoponus', Israel Oriental Studies II (1972), 320-352, and G. Troupeau, 'Un epitomé arabe du "de contingentia mundi" de Jean Philopon', Mémorial André Jean Festugière (Cahiers d'Orientalisme 10). Geneva, 1984, 77-88. In general, Simplicius is not always fair when quoting, or just referring to, the arguments of his opponents, see M. Rashed, 'A "new" text of Alexander on the soul's motion', R. Sorabji (ed.), Aristotle and After. (BICS Suppl. 68). London, 1997, 181-197.

Read Latest
Index for 2002
Change Greek Display
Books Available for Review

HTML generated at 13:28:09, Friday, 03 April 2009