Note 19 — AND HIS PREDECESSORS
Reading edition
René Descartes, Oeuvres, Charles Adam and Paul Tannery, Paris, 1897-1910, vol. 2, p. 597 (letter to Mersenne, 16 Oct., 1639), and vol. 11 (Le Monde), p. 39. The original definition can be found in Aristotle, Physics, translated by P. H. Wickstead and F. M. Cornford, Loeb Classical Library, London, 1934, 201a10. Aquinas rephrases the definition as "Motus est actus existentis in potentia secundum quod huius modi." See St. Thomas Aquinas, Opera omnia, Antwerp, 1612, vol. 2, Physicorum Aristotelis expositio, lib. 3, lect. 2, cap. a, p. 29.