[17] Ibid. p. 410, a. 20.
[18] Ibid. p. 410, b. 10.
Some philosophers have assumed (continues Aristotle) that soul pervades the whole Kosmos and its elements; and that it is inhaled by animals in respiration along with the air.[19] They forget that all plants, and even some animals, live without respiring at all; moreover, upon this theory, air and fire also, as possessing soul, and what is said to be a better soul, ought (if the phrase were permitted) to be regarded as animals. The soul of air or fire must be homogeneous in its parts; the souls of animals are not homogeneous, but involve several distinct parts or functions.[20] The soul perceives, cogitates, opines, feels, desires, repudiates; farther, it moves the body locally, and brings about the growth and decay of the body. Here we have a new mystery:[21] — Is the whole soul engaged in the performance of each of these functions, or has it a separate part exclusively consecrated to each? If so, how many are the parts? Some philosophers (Plato among them) declare the soul to be divided, and that one part cogitates and cognizes, while another part desires. But upon that supposition what is it that holds these different parts together? Certainly not the body (which is Plato’s theory); on the contrary, it is the soul that holds together the body; for, as soon as the soul is gone, the body rots and disappears.[22] If there be anything that keeps together the divers parts of the soul as one, that something must be the true and fundamental soul; and we ought not to speak of the soul as having parts, but as essentially one and indivisible, with several distinct faculties. Again, if we are to admit parts of the soul, does each part hold together a special part of the body, as the entire soul holds together the entire body? This seems impossible; for what part of the body can the Noûs or Intellect (e.g.) be imagined to hold together? And, besides, several kinds of plants and of animals may be divided, yet so that each of the separate parts shall still continue to live; hence it is plain that the soul in each separate part is complete and homogeneous.[23]
[19] Ibid. ii. p. 404, a. 9: τοῦ ζῆν ὅρον εἶναι τὴν ἀναπνοήν, &c. Compare the doctrine of Demokritus.
[20] Ibid. v. p. 411, a. 1, 8, 16.
[21] Ibid. a. 30.
[22] Aristot. De Animâ, I. v. p. 411, b. 8.
[23] Ibid. b. 15-27.
Aristotle thus rejects all the theories proposed by antecedent philosophers, but more especially the two following:—That the soul derives its cognitive powers from the fact of being compounded of the four elements; That the soul is self-moved. He pronounces it incorrect to say that the soul is moved at all.[24] He farther observes that none of the philosophers have kept in view either the full meaning or all the varieties of soul; and that none of these defective theories suffices for the purpose that every good and sufficient theory ought to serve, viz., not merely to define the essence of the soul, but also to define it in such a manner that the concomitant functions and affections of the soul shall all be deducible from it.[25] Lastly, he points out that most of his predecessors had considered that the prominent characteristics of soul were — to be motive and to be percipient:[26] while, in his opinion, neither of these two characteristics is universal or fundamental.
[24] Ibid. a. 25.