Since then to him the Platonic ideas were nothing apart from the individual objects, Aristotle could find no principle of movement or change in them; so he claimed that the doctrine of ideas was sterile and came to naught. In his own system he enumerated four principles or causes, which he insisted, however, are only known to us from individual things: the material cause (τὸ ἐξ oὗ γίνεταί τι, ἡ ὓλη), the formal cause (τὸ εἶδος, ἡ μορφή), the efficient cause (τὸ ὅθεν ἡ ἀρχή), and the final cause (τὸ oὗ ἕνεκα, τὸ τέλος). To make his meaning clear let us use in part his own illustrations: the material cause of the statue is the bronze of which it is made, just as in the example of the pot which we used a little while ago, the clay was its material cause; the formal cause is the idea of the statue, or of the pot, or of the octave in music, which the artist has in mind; the artist himself is the efficient cause; and the object of the action, the completed pot, statue, or whatever it may be, is the final cause.[215] That is to say the statue exists potentially in the bronze, the pot potentially in the clay, the octave potentially in the musical sounds, but these things can be called in actual existence only by the operation of the other three causes; and the same thing holds true in animate nature. It is possible therefore to state the matter generally and to say that in every case the individual is produced by the operation of the formal, efficient, and final causes on the material cause, bringing to actuality the potentiality in matter. Of course we may regard the formal, efficient, and final causes as different aspects of the same formal cause—a thing which Aristotle himself does in more than one passage,[216] so that in the last analysis he regards matter and form as the two causes or principles of things. These two are to him correlatives, each completing the other, although he gives greater importance to the formal than to the material cause. These two causes, he says, attract each other; and their union brings about movement, which is always the evolution of something from something else.
From these considerations I trust that it is evident that Aristotle regarded every object of nature, whether animate or inanimate, as the product of causation; behind each individual he found another individual, and he saw that each object was the result of conscious causal activity. So, looking on the world with scientific eyes, he found therein continuous movement dependent on a chain of causes, and he pointed out that such a chain requires a first cause which must be the source of all activity. This first cause was to him Mind, pure Thought, God, conscious, eternal, and good. But his First Cause was at the same time the Final Cause, for the supreme Mind conceives the end toward which all creative activity is tending, that is, it acts with intelligence so that the world is the creation of intelligence and is directed toward wise ends.[217] The order of the universe bears witness to the Mind which set it in order, and which keeps it in motion, all for intelligent ends; for to use Aristotle’s own expression, “God and Nature do nothing without a purpose.”[218] Thus Aristotle introduced into theology cosmological and teleological arguments for the existence of God.
But when Aristotle defines God as pure Thought, the supreme Idea or Form, with no admixture of matter, it might seem that he had contradicted himself. It will be remembered, however, that in his system matter and form do not stand quite on an equality—matter is somewhat subordinate to form. He regarded matter as the point of departure for something higher—the clay being antecedent and lower than the pot, the bronze than the statue—for the higher product always results from the operation of the formal cause on the material. Of course in our illustrations the bronze and the clay are not absolute matter, but only matter with reference to the higher products evolved from them—the pot and the statue. Indeed Aristotle did not suppose that there was such a thing as absolute matter existing by itself, but he rather thought of his material cause as matter not yet formed, the germ from which the actual object was to be developed by the operation of the formal cause. Now he saw in the universe an ascending scale of existence, just as today we recognize such a scale in the animal world, each stage being more perfect than that below it; he pointed out that with reference to the lower, each higher stage was ideal, but material with reference to that which was still higher. So in every stage the idea, the form, preceded and conditioned the material element, and in a sense we may correctly say that Aristotle gradually refined away his material element in the ascending scale. At the summit Aristotle placed the perfect and supreme Idea, God, the eternal antecedent of all activity, the prime mover of the universe. So in the end he identified God and Form. Strictly speaking in his system God could not be a resultant of form and matter, for then God would not be the ultimate being, but some cause would lie behind him; and he would not be perfection, since some potentiality, the characteristic of matter, would still reside in him. As a matter of fact Aristotle in a number of passages identifies his ultimate material and form (ἡ ἐσχάτη ὔλη καὶ ἡ μορφὴ ταὐτό);[219] not that he would have granted that there was a material element in the Supreme Being; but in the light of what we have just said we can understand how he might have held that the ultimate material and God were identical.[220]
It readily follows from Aristotle’s concept of God as the prime mover, the source of all activity in the world, that God can be but one. Monotheism is the logical result of the Aristotelian reasoning. Moreover it was inevitable that Aristotle should make God transcendent, that is, that he should place him above all objects of the natural world, since if the First Cause is pure thought unmixed with matter, he cannot be immanent in material things. The immateriality which Plato gave to his ideas, his pupil transferred to God.
Midway between the natural and the supernatural worlds Aristotle placed man, whom he regarded as bound to the world of nature by his body and the lower elements of his mind, but connected with God through his reason, for he held that the human mind possessed attributes of the divine intelligence. Aristotle’s psychology was based on his belief that there was a purpose in all nature, and on his view that in the individual were always united form and material. With reference to animate beings he showed that they had their formative principle within them, which brought to actuality the material which had the potentiality of life, and which determined the purpose for which the individual creature existed. This formative principle was then for him the soul of the animate being, whether plant, lower animal, or man; it was the internal principle which determined the processes of nutrition, growth, and decay common to all animate creatures, and no less the functions peculiar to the lower and the higher animals throughout the scale of life. The soul of a plant, then, he defined as the assimilative principle (τὸ θρεπτικόν) But creatures of the next, higher stage, the so-called lower animals, he saw had senses, desires, and self-movement; to their souls therefore he assigned the additional elements of sensation (τὸ αἰσθητικόν), appetite (tὸ ὀrektikόn), and motion (τὸ κινητικόν). Finally, he said, the human soul had mind (νοῦς) in addition to the elements possessed by the lower animals and plants, for man has the power of thought and reflection. Therefore man is the highest creature, the most perfect organism in the natural order.
But the human mind, as Aristotle pointed out, has two activities: it concerns itself with knowing and with reasoning; it is passive, receptive, in that it receives ideas from without, and creative in that it can reflect on its own ideas and so create new ideas which are in no sense dependent on material objects—are, as we say, abstract ideas. To this creative part of man’s soul, to his reason alone, did Aristotle grant eternal existence and immortality. All other activities of the soul—knowing, moving, seeking, feeling, and assimilating—he held to be bound to the body and hence to perish with it; but the reasoning element he maintained was in no way dependent on the material world, was always active, and therefore it alone was immortal and eternal.[221] Yet after establishing the immortality of the reasoning element Aristotle failed to define the fate of the immortal human reason after death; of joys or pains beyond the grave he gave no description.
In ethics Aristotle taught that the highest human good was that happiness which results when man’s mind under the direction of reason is active toward virtuous ends; that moral virtue is a habit which is acquired by cultivation, a condition which is attained when the appetites are controlled by the will and guided by the reason. Now in the Aristotelian system man alone was regarded as capable of moral action. The animals are guided by appetite and lack intelligence to direct them; God is pure reason and therefore we cannot attribute to him any moral qualities; but man possesses the characteristics of the lower creatures and has at the same time the divine element, the reason, which connects him with God. Therefore since man is endowed with reason which can either prompt the will to check the appetite or bid the will let appetite go its way, he is capable of choice and so of morality. By thus emphasizing the controlling function of the will Aristotle prepared the way for the Stoics, as we shall see in our next lecture. Virtue in the active life of society was to him always the mean between two extremes, both of which were themselves vices. Courage, for example, lies midway between cowardice and rashness; temperance between indulgence and abstinence; and so on through the whole range of the ethical virtues. Above these virtues of the active life, Aristotle placed a higher rank—the intellectual virtues of wisdom, knowledge, good-sense, practical insight, etc., which result from a harmony of the active and the receptive parts of the intellect. Highest of all he put the speculative activities of the intellect, which he regarded as its proper and most constant function. This “theoretical” or “contemplative” life (θεωρητικὸς βίος) he said brought man his highest happiness just because it was his highest activity. Yet Aristotle could not hold out the hope that men could attain this joy fully or in great numbers; he saw that the greater part of human life was concerned with practical virtues, with good character; and he believed that only when man was good in everyday life could he hope to rise to the contemplative life, but that in that life, at moments, he might catch glimpses of the happiness which belonged continuously to God.[222]
Unquestionably Aristotle did a large service in putting ethics on a more scientific basis than his predecessors had done, but his chief contributions to the subject with which we are now concerned were in the field of theology. There, as we have already noted, he established the cosmological and teleological arguments for the existence of God; and he also introduced a clearly defined transcendentalism, thus making explicit what had been implied in parts of Plato’s teachings. Yet he failed to provide that satisfaction for religious hopes and fears which men desired, and so, as I have said, the cold scientific reasoning of the Stagirite had far less influence in religion than the enthusiastic thought of his teacher until after many centuries had passed.
Although we may readily recognize that the influence of philosophy on the religious belief of the most enlightened in this time was great, we may still question whether it had any considerable influence on the religious customs of the people. Practice is always more conservative than thought, and we find that the thinkers who did most to destroy traditional theology frequently conformed to the traditional worship of the common man. So Socrates sacrificed in the usual way to the gods, although he held advanced ideas with regard to prayers and oaths. No doubt Plato and Aristotle passed for pious so far as their religious practices were concerned, in spite of the fact that they put new content into ancient forms. The former frequently made the speakers in his dialogues refer to the gods in quite the traditional way, and in his Timaeus he set forth a kind of systematic theology; in his Laws, written in his old age as a supplement to his Republic, he planned for his ideal state a religious organization, involving a plurality of gods, not dissimilar to that of the actual Athenian state; he represented his chief spokesman as proving the existence of the gods, giving warrant for the familiar practices of religion, and justifying the ways of gods to men; moreover he proposed to have statutes against impiety and the introduction of religious rites not recognized by law.[223] Aristotle clearly had slight respect for the common notions as to the gods, but for all that he regarded the worship of many gods as natural, and he thought that worship was indispensable for the existence of a state; therefore in his Politics he made a place for a polytheistic religion, defined the duties of priests and other sacred officials, and provided that all the expenses of public worship should be borne by the state.[224] The charge, prompted by political passion, brought against Aristotle for impiety in deifying Hermias, the prince of Mysia, shows that he was not regarded as atheistic.