Abstract

This paper is concerned with an important variant reading discovered at the beginning of Book VIII of Aristotle’s _Physics_. The reading is found in J, the oldest manuscript of this work (Vind. phil. gr. 100, 9th c.): at VIII 1.250b13, J reads εἰ ἦν, “if it [_scil_. the movement] was”, instead of ἀεὶ ἦν, “it always was”, the only reading so far taken into account. Several early witnesses support J: E (Paris. gr. 1853, 10th c.), the Greek into Latin translation by James of Venice (first half of the 12th c., _si erat_); the earliest Arabic version (_ap_. Jabir ibn Hayyan, انكنات, “if [the movement] was”). Such early sources thus agree as witnesses of a hypothetical premise concerning the eternity of cosmic motion against the standard vulgate text of the _Physics_. Once the if-reading at 250b13 is accepted, as opposed to the vulgate, Aristotle’s conclusion about the eternity of motion will apply not absolutely, but under the condition of the given premise that in no plausible way could motion have begun in time. The difference is important on several grounds. In particular, it fits better with the manner in which the argument is then developed by Aristotle throughout chapter 1 of _Phys_. VIII and with the parallel discussion about the eternity of the cosmos in _De caelo_ I 10 and _Metaphysics_ Λ 6. However, favouring the variant reading of J for _Phys_. 250b13 raises the problem of evaluating with special care the authority of manuscript J for the textual constitution of the _Physics_, which remains an open question for future scholarship.