In order to classify facts, and to arrive at the uni- versal from the particular, we must reason ; and the theory of reasoning is logic, which, according to Aris- totle, is the organon or instrument of all science, quoad formam. In this field the pre-eminence of Aristotle is indisputable ; he may, indeed, be said to have in- vented logic as the formal part of reasoning, and it remains to this day substantially what he made it. Grote observes that "what was begun by Socrates, and improved by Plato, was embodied as a part of a comprehensive system of formal logic by the genius of Aristotle ; a system wdiich was not only of extraor- dinary value in reference to the processes and contro- versies of its time, but which also, having become in- sensibly worked into the minds of instructed men, has contributed much to form what is correct in the hab- its of modern thinking. Though it has now been en- larged and recast by some modern authors (especially ly Mr. John Stuart Mill in his admirable System of Logic) into a structure commensurate with the vast increase of knowledge and extension of positive meth- od belonging to the present day, we must recollect that the distance, between the best modern logic and that of Aristotle is hardly so great as that between Aristotle and those who preceded him by a century — Empedocles, Anaxagoras, and the Pythagoreans ; and that the movement in advance of these latter com- mences with Socrates" {History of Greece, pt. ii, ch. lxviii).
In Psychology Aristotle anticipated a great deal of what is called "mental philosophy" at present. The soul, he says, is an entitj7 ; not the product of matter or of organization, but distinct from the body, though not separable from it as to its form (De Anima, ii, 1). In this principle he agrees with Plato, and it saves his doctrine from becoming wholly materialistic, a tendency natural to the empirical method. "The faculties (SvvafiUQ) of the soul are production and nu- trition (De Anim. ii, 2, 4; De Gencr. Anitn. ii, 8), sensation (Ibid, ii, 5, G, 12 ; iii, 12), thought (to dia- vo7]tik6i'), and will or impulse. His remarks are par- ticularly interesting on the manifestations of the cog- nitive powers (DeAnim. ii, 6; iii, 12 sq. ; De Sensu et Sensibili), i. e. on the senses ; on common sense (icoivi) a'iaOrjffuS) ; the first attempt toward a clearer indica- tion of consciousness (Ibid, iii, 1 sq.), on imagination, reminiscence, and memory (Ibid, iii, 3, et De Memo- rial. The act of intuition and perception is a recep- tion of the forms of objects ; and thought is a recep- tion of the forms presupposed by feeling and imagina- tion (Ibid, iii, 4). Hence a passive (ttoOijtikuc, intel- lectus patiens) and an active, understanding (ttoitjtikoc vovg, intellectus agens). The first implies receptivity for those forms, therefore it has the closest relation with the faculty of feeling, and hence with the body; to the latter, which elaborates those forms into judg- ing (virdkafifidvuv) and inferring (\oyi'^«T0ai), and which moreover itself thinks, appertains indestructi- bility (immortality without consciousness or memory) (De Anim. ii, 1-G; iii, 2 sq. 5). Thought itself is* a power separate from the body, coming from without into man (De Gencr. Anim. ii, 3), similar to the ele- ment of the stars (Cie. Acad. Quajst. i, 7). Further, the understanding is theoretical or practical ; it is the latter, inasmuch as it proposes ends and aims. The will (ufJt'Ctc) is an impulse directed toward matters of practice— that is to say, toward t:ood ; which is real or apparent, according as it procures a durable or a tran- sient enjoyment (fie A n. iii, 9-11 ; Eth. iii, vi) : opt$ic is I
subdivided into povXiimg and iiriBvfiia — thcuill, prop- erly so called, and desire. Pleasure is the result of the perfect exertion of a power — an exertion by which the power again is perfected. The noblest pleasures spring from reason (Ethic, x, 4, 5, 8)." — Tennemann, §145.
From Psychology we proceed to Metaphysics, or " the first philosophy," as Aristotle called it, i. e. the attempt to solve the problem of being. Had Aristotle adhered strictly to his own empirical method, he would have confined himself to the relative, and not sought the absolute at all. His prima philosophia deals with the unchangeable, while physical science deals with change or movement. " Matter," he said, " exists in a threefold form. It is, I. Substance, perceptible by the senses, which is finite and perishable. This sub- stance is either the abstract substance, or the substance connected with form (t'idoc). II. The higher sub- stance, which, though perceived by the senses, is im- perishable, such as are the heavenly bodies. Here the active principle (tvipyeta) steps in, which, in so far as it contains that which is to be produced, is un- derstanding (vovcf). That which it contains is the purpose (to ov evtica), which purpose is realized in the act. Here we have the two extremes of potentiality and agency, matter and thought. The often-men- tioned entelechic is the relation between these two extremes. It is the point of transition between diva- pig and ivtpyua, and is accordingly the cause of mo- tion, or efficient cause, and represents the soul. III. The third form of substance is that in which the three forms of power, efficient cause and effect, are united — the absolute substance, eternal unmoved, God him- self" (Lewes, Hist, of Philosophy, ii, 126). As to the relative place of the idea of God in the systems of Plato and of Aristotle, Maurice well remarks that "it cannot be denied that the recognition of an absolute being, of an absolute good, was that which gave life to the whole doctrine of Plato, and without which it is unmeaning ; that, on the contrary, it is merely the crowning result, or, at least, the necessary postulate of Aristotle*s philosophy. In strict consistency with this difference, it was a. being to satisfy the wants of man which Plato sighed for ; it was a first cause of things to which Aristotle did homage. The first would part with no indication or symbol of the truth that God has held intercourse with men, has made himself known to them ; the second was content with seeking in nature and logic for demonstrations of his attributes and his unity. When we use personal lan- guage to describe the God of whom Plato speaks, we feel that we are using that which suits best with his feelings and his principles even when, through rever- ence or ignorance, he forbears to use it himself. When we use personal language to describe the deity of Aristotle, we feel that it is improper and unsuitable, even if, through deference to ordinary notions, or the difficulty of inventing any other, he resorts to it him- self" (Maurice, Moral and Metaph. Philosophy, ch. vi, div. iii, § 5).