Metaphysics.— First Philosophy (the term Metaphysics is not used by Aristotle, but is a word applied to the First Philosophy on ac count of its being placed after the treatises on Physics by the early editor of the works) is the philosophy of first principles as such; sec ond philosophy or physics is the philosophy of these principles applied to concrete phenomena, the phenomena of motion and matter. Aris totle is a disciple of Plato and, like his master, he viewed the world from the standpoint of teleology. The cosmic processes are determined by final causes. He makes more of facts than Plato does, has a much larger mass of empiri cal data for his constructions and is more catholic in his scientific interests. His meta physics, however, like Plato's, is based on high speculative ideas and he explains the world order by means of these general and ultimate principles, so that he is not a realist in the sense of confining reality merely to particular facts. Like Plato, he sought the essence of phenomena in the concept and law, but unlike Plato he sought it in a concept given in the phenomena as their inner principle of development and not in a transcendent principle. If there is no concept or universal there can be no scientific knowledge. The concept is not, however, an idea isolated from particular thinly, but as the universal reality it is immanent in particulars (universalia in re not ante rem), the individ ual being the only self-existent real. Against Plato's doctrine of ideas Aristotle brings the following criticisms: (1) The Platonists fur nish no adequate proof of the existence of ideas as hypostasized entities; (2) The Platonic ideas, because transcendent, cannot explain the phenomenal world, which is left without a principle of motion; (3) The world of ideas is only a reduplication of the world of sense in its generic aspect; (4) The explanation of the relation of the ideal to the sensible world by the terms archetype, pattern, image, etc., is only metaphorical. The universal is real as the formative principle in things, giving to them their generic character, while matter is the principle of individuality. Form and matter are explanatory of genus and individual. In every particular thing, with the exception of God or the Prime Mover (who is pure form), the two principles of form and matter are pres ent; form making the classification of things and scientific knowledge possible, and matter making possible the concreteness of objects. Form and matter are two aspects of individual things and are not really, but only notionally, separable. Everything is both form and sub strate, idea and matter, significance and stuff, soul and body, with the single exception of the Supreme Being. Form is the moving principle of development and matter is the passive poten tiality. Plastic stuff or matter is molded after generic patterns. In nature's processes Aris totle calls them energy and potentiality. The real is an explication of a prior potential. The transition of a thing from a condition of poten tiality to a condition of actuality is ac complished by some form of motion. Motion in turn (which is of several kinds: spatial, that is, locomotion; qualitative, that is, trans mutation of substances; quantitative, that is, growth) implies a moving cause, and any given moving cause an antecedent cause and so the causal regress would be endless, were we not to posit a Prime Mover or uncaused First Cause. The First Cause is the origin and source of all motion and life. As motion is eternal, so the Prime Mover is eternal; it is also immaterial, passionless and motionless, for the Prime Mover causes motion merely as an ideal toward which matter strives in the processes of nature, analogously to the power of attraction in beauty. The activity of God is pure thought or thought turned upon itself, which theoretic life is for Aristotle the perfect type of life. Between God, as pure form, and matter, as formless stuff—the extreme cos mic principles— Aristotle places the world of natural phenomena, which are all composites of the two principles. His doctrine of the Prime Mover is a direct product of his philos ophy and is the first attempt to found a theis tic theory on a philosophical basis. Aristotle specifies as the four causes operative in nature the formal, final, efficient, and material. But as form contains within itself the principles of efficiency, purpose and meaning, these four causes are reducible to his dualism of form and matter. As an example of his application of the four causes, a statue presupposes: (1) matter, for example, day, wood or marble; (2) a form or idea in the artist's mind; (3) an ef ficient cause, such as the energy applied to tools; (4) a motive or purpose.
Physics.— While the metaphysics treats of being as such, of the unconditioned, of the ulti mate principles explanatory of reality, Physics treats of the contingent, the conditioned and of the quantitative and qualitative relations of things. In the philosophy of nature's phenom
ena, the concept of motion plays the chief role, effecting the transition of potentiality to ac tuality and having its ultimate source in the Prime Mover. The whole of growth and de velopment proceeds from one form of being to another form of being, but not from nothing to something, or from non-existence to exist ence. For Aristotle as for all the Greekphilos ophers the maxim holds: ex 'Ado nihil fit.
In ert matter is the most formless element in na ture and man is the stage in which the high est form manifests itself. Between these na ture exhibits a graded scale of development, that is, from the most inorganic to the highest organism. This scale itself is static and not a scale of evolution in the modern sense. The scale of beings is a fixed cosmic hierarchy, not determined by protoplasmic conditions plus en vironment. The Aristotelian world is a teleo logical system, the eternal forms working them selves out in plastic and contingent matter with reference to fixed final goals, the whole exhib itingplan, not planless, as Aristotle says, (like a bad As the Prime Mover is per fect so the world shows that degree of perfec tion which is possible with the contingency and imperfection of matter. God is both in the world and outside of it as the transcendent cause of its order, just as the discipline of an army is in the army and outside of it in the person of the general. The universe is con ceived by Aristotle to be spherical in form, not infinite. Its periphery consists of the region of the fixed stars, which revolve in a perfectly circular motion. They do not move freely in space, but are attached to the ethereal body of the outer heaven and move as a rider in a char iot. Their motion is caused immediately by the Prime Mover and being nearest to him, their motion is most perfect. The earth is at the centre of the universe and is fixed. Be tween the centre and the circumference are the seven planets including the sun and moon. The motion of these, although concentric with the circumference, is less perfect, deviating from an exact circle. The earth is the region of rectilinear motion. The general presuppo sitions of motion are space and time. Space is, in Aristotle's conception, strictly speaking, only place, that is, it is the room occupied by body, and time is the measure of motion with reference to earlier and later. Motion being endless time as the measure of its discrete mo ments is infinite. Space is finite, for there is no space outside the corporeal world. The ele ments in the cosmos are fire, earth, air, water and ether. Of these the first four are subli matory. The celestial spheres consist of pure ether.
Psychology.—Aristotle defines soul as the (complete realization of a body endowed with the capacity of life.) Every body, therefore, that has life, has soul, and psychology in the narrow sense would be a branch of biology. The physical world, according to Aristotle, is divided into two realms, the inorganic and the organic. The characteristic mark of the latter is the possession of life, or (soul.) Soul is syn onymous with the principle of life, by virtue of which a thing is endowed with the power of self-movement. Life is the universal form of organic activity, feeling and reason are spe cific forms of the same power. The highest manifestation of psychical activity is rational thought. There are four main forms in which life manifests itself : (1) Nutrition, growth, decay and the power in things to reproduce, each after its kind, whereby the continuity of life is maintained; (2) locomotion; (3) sen sation; (4) reason. These various types of life are forms of self-movement. The first form is found in the plant world as well as in the ani mal world, the last three only in the animal world. Soul as life is found in every part of the body, to which it is related as form to mat ter. The heart as the anatomical and physi ological centre is also the life-centre. The heart, therefore, and not the brain, is the or gan of consciousness, for consciousness is one of the forms of life. The processes of know ing or conscious life are developed in these stages: (1) sensation; (2) imagination, the power of using images of absent objects, com bined with memory; (3) rational thought Rea son, according to Aristotle, is two-fold, crea tive and passive. All knowledge, in the last analysis, is derived from sense-perception. The mass of sense-perceptions which are held to gether by memory and stored in the central sense (sensorium) are the passive reason, that is, they constitute the matter which the creative reason transforms into conceptual knowledge. The two stand related to each other, therefore, as form to matter, actuality to potentiality.