Simplicius of Cilicia, the Neoplatonist who studied under Ammonius at Alexandria and Damascius at Athens, wrote this commentary on the eight books of Aristotle's Physics in the sixth century CE. It proceeds by lemmas: a passage of Aristotle is quoted, then explained at length, with the readings of the copies compared and the views of earlier interpreters weighed, among them Alexander of Aphrodisias, Themistius, Porphyry and Eudemus' own Physics. Throughout, Simplicius reads Aristotle as agreeing with Plato. The commentary survives complete in medieval manuscripts, one part for each book of the Physics.
The notes on Book I quote Parmenides, Melissus and other early philosophers at length, and are the main source for much of Parmenides' poem. Book II covers physis, the causes, chance and spontaneity, and necessity; Book III motion and the infinite; Book IV place, void and time, with two long digressions of Simplicius' own, on place and on time. Books V to VII treat change, continuity, Zeno's arguments and the relation of mover to moved, with notes on the titles and order of Aristotle's books. The commentary on Book VIII, on the eternity of motion and the unmoved first mover, opens with a polemic against John Philoponus, whom Simplicius does not name, for his books against the eternity of the heavens.
Simplicius of Cilicia Commentary on the Physics: summary and contents (PDF)
Simplicius of Cilicia Commentary on the Physics: summary and contents (Markdown)
Contents
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Αʹ Book I
Simplicius opens with the aim of the Physics, set within Aristotle's division of philosophy into practical and theoretical, and of the theoretical into natural, mathematical and theological. Book I reviews the earlier thinkers and seeks the principles of natural things, and here Simplicius quotes Parmenides, Melissus and other early philosophers at length and examines Parmenides' claim that what is is one. The last notes reach Aristotle's conclusion on which principles there are and how many.
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Βʹ Book II
After a review of the principles found in Book I, these notes follow Aristotle from the elements of natural things to physis and the other causes: form as physis, the difference between physics and astronomy, where Simplicius quotes Geminus by way of Alexander, the modes of cause, chance and spontaneity, and necessity among natural things. Causes in energeia and in dynamis are illustrated by the builder and the house that outlasts him, and the closing notes treat the saw whose purpose requires iron teeth.
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Γʹ Book III
Motion comes next because physis was defined as a principle of motion, Simplicius explains, and the continuous, the infinite, place and time must follow it; his notes then take Aristotle through the definition of motion and the infinite in Book III. Among them is the Pythagorean pairing of the even with the unlimited and the odd with limit, shown by adding odd numbers to a square. The last pages, gapped in places, hold that magnitude is infinite only potentially.
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Δʹ Book IV
Every natural body is in a place and every motion is measured by time, so Book IV turns to place, void and time; Simplicius follows Aristotle through each, with long digressions of his own on place and on time. On void he discusses bodies that move by exchanging places, spinning tops and water swirling in a vessel, together with Strato's views; on time he answers the difficulties, Strato's among them, and sends any reader still unsatisfied to Damascius' On Time.
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Εʹ Book V
Change in general is here set apart from motion proper, since coming to be and passing away are changes but not motions. Simplicius explains why Aristotle and his followers counted Book V with the earlier books, called On Principles or Physics, rather than with the three books On Motion, then treats change of kind, of size and of place; the terms together, apart, touching, between, in succession and continuous; what makes a motion one; and which motions and rests are contrary to each other.
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Ζʹ Book VI
Why the sixth book of the Physics is lettered zeta, and where the Physics proper ends and the books On Motion begin, are settled first, with Andronicus and a letter of Theophrastus to Eudemus as witnesses. Simplicius then follows Aristotle's proofs on the continuity of change: what has changed is already in what it changed to, Zeno's arguments are answered, the partless moves only accidentally, and only circular motion can last for infinite time.
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Ηʹ Book VII
Book VII circulated in two versions, Simplicius notes; Eudemus skipped it as superfluous and Themistius passed over many of its arguments. Simplicius suggests that Aristotle wrote it before the fuller proofs of Book VIII. His notes treat movers and moved, alteration, and knowledge as a coming to rest, set beside Plato's Timaeus on the newborn, without understanding once bound in a mortal body, and end with the falling millet seed and the limits of proportion between power, weight and time.
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Θʹ Book VIII
Aristotle's last book of the Physics proves the first motion eternal and every moved thing dependent on an unmoved first mover. Simplicius opens against John Philoponus, a contemporary he does not name, who had written five books against the eternity of the heavens, and takes up a further book of his here. The notes go on to what moves itself, comparing readings in the copies with Alexander's text, and end with the first mover shown to be partless and without magnitude.