THE WILL IN NATURE.
taken for granted as a matter of course and only occasionally brought explicitly into prominence; nevertheless, in order to make the case quite certain, I will point out a few passages from the earliest to the latest authors in which it is specially stated. In Phaedrus, 1 Plato makes the distinction between that which moves spontaneously from inside (soul) and that which receives movement only from outside (body), τσ υφ εαυτσυ κινουμενον και το, ω εξωδεν το κινεισδαι. 2 Aristotle establishes the principle in precisely the same way: απαν το φερομενον η υφ εαυτου κινειται, υπ αλου (quidquid fertur a se movetur, aut ab alio). 3 He returns to the subject in the next Book, chap. 4 and 5, and connects it with some explanatory details which lead him into considerable perplexity, on account precisely of the fallacy of the antithesis. 4 In more recent times again J. J. Rousseau brings forward the same antithesis with great naiveté and candour in his famous Profession de foi du vicaire Savoyard: 5 "J'aperçois dans les corps deux sortes de mouvement, savoir: mouvement communiqué et mouvement spontané ou volontaire: dans le premier la cause motrice est étrangère au corps mû; et dans le second elle est en lui-même" [I observe in bodies two kinds of motion, namely, communicated or spontaneous or voluntary motion. In the first case the motive cause is foreign to the body moved; in the second it is inherent in the body itself]. But even in our time and in the stilted, puffed-up style which is peculiar to it, Burdach holds forth as follows 6 "The cause that determines a movement lies either inside or outside of that which
1 Plato, Phaedrus, p. 319 Biponti edition
2 "That which is moved by itself and that which is moved from outside." [Tr.] And we find the same distinction again in the 10th Book De Legibus, p. 85. [After him Cicero repeats it in the two last chapters of his Somnium Scipionis. Add. to 3rd ed.]
3 " All that is moved, is moved either by itself or by something else." [Tr.] Aristotle, Physics, vii. 2.
4 Maclaurin, too, in his Account of Newton's Discoveries, p. 102, lays down this principle as his starting-point. [Add. to 3rd ed.]
5 Émile, iv. p. 27. Biponti edition.
6 Burdach, Physiologie, vol. iv. p. 323.
PHYSICAL
