Part 5

Two more remarks may be made in this connection. (1) The prominence of the notion of "end" gives Aristotle's philosophy a thorough-going "ideological" character. God and Nature, he tells us, do nothing aimlessly. We should probably be mistaken if we took this to mean that "God and Nature" act everywhere with conscious design. The meaning is rather that every natural process has a last stage in which the "form" which was to begin with present in the agent or "source of change" is fully realised in the matter in which the agent has set up the process of change. The normal thing is _e.g._ for animals to reproduce "their kind"; if the reproduction is imperfect or distorted, as in monstrous births, this is an exception due to the occasional presence in "matter" of imperfections which hinder the course of development, and must be regarded as "contrary to the normal course of Nature." So hybrid reproduction is exceptional and "against Nature," and this is shown by the sterility of hybrids, a sort of lesser monstrosity. Even females, being "arrested developments," are a sort of still minor deviation from principle. (2) It may just be mentioned that Aristotle has a classification of efficient causes under the three heads of Nature, Intelligence (or Man), and Chance. The difference between Nature and Man or Intelligence as efficient causes has already been illustrated. It is that in causation by Nature, such as sexual reproduction, or the assimilation of nutriment, or the conversion of one element into another in which Aristotle believed, the form which is superinduced on the matter by the agent already exists in the agent itself as _its_ form. The oak springs from a parent oak, the conversion of nutriment into organic tissue is due to the agency of already existing organic tissue. In the case of human intelligence or art, the "form" to be superinduced exists in the agent not as _his_ characteristic form, but by way of representation, as a contemplated design. The man who builds a house is not himself a house; the form characteristic of a house is very different from that characteristic of a man, but it is present in contemplation to the builder before it is embodied in the actual house. A word may be added about the third sort of efficient causality, causation by chance. This is confined to cases which are exceptions from the general course of Nature, remarkable coincidences. It is what we may call "simulated purposiveness." When something in human affairs happens in a way which subserves the achievement of a result but was not really brought about by any intention to secure the result, we speak of it as a remarkable coincidence. Thus it would be a coincidence if a man should be held to ransom by brigands and his best friend should, without knowing anything of the matter, turn up on the spot with the means of ransoming him. The events could not have happened more opportunely if they had been planned, and yet they were not planned but merely fell out so: and since such a combination of circumstances simulating design is unusual, it is not proper to say that the events happened "in the course of Nature." We therefore say it happened by chance. This doctrine of chance has its significance for mediaeval Ethics. In an age when the Protestant superstition that worldly success is proof of nearness to God had not yet been invented, the want of correspondence between men's "deserts" and their prosperity was accounted for by the view that the distribution of worldly goods is, as a rule, the work of Fortune or Chance in the Aristotelian sense; that is, it is due to special coincidences which may look like deliberate design but are not really so. (See the elaborate exposition of this in Dante, _Inferno_, vii. 67-97.)

*Motion*.--We have seen that causation, natural or artificial, requires the production in a certain "matter" of a certain "form" under the influence of a certain "agent." What is the character of the process set up by the agent in the matter and culminating in the appearance of the form? Aristotle answers that it is Motion (_kinesis_). The effect of the agent on the matter is to set up in it a motion which ends in its assuming a definite form. The important point to be noted here is that Aristotle regards this motion as falling wholly within the matter which is to assume the form. It is not necessary that the agent should itself be in motion, but only that it should induce motion in something else. Thus in all cases of intentional action the ultimate efficient cause is the "idea of the result to be attained," but this idea does not move about. By its presence to the mind it sets something else (the members of the body) moving. This conception of an efficient cause which, not moving itself, by its mere presence induces movement in that to which it is present, is of the highest importance in Aristotle's theology. Of course it follows that since the motion by which the transition from potentiality to actuality is achieved falls wholly within the matter acted upon, Aristotle is not troubled with any of the questions as to the way in which motion can be transferred from one body to another which were so much agitated in the early days of the modern mechanical interpretation of natural processes. Aristotle's way of conceiving Nature is thoroughly non-mechanical, and approximates to what would now be called the ascription of vital or quasi-vital characteristics to the inorganic. As, in the causality of "art" the mere presence of the "form" to be embodied in a given material to the mind of the craftsman brings about and directs the process of manufacture, so in some analogous fashion the presence of an efficient cause in Nature to that on which it works is thought of as itself constituting the "efficiency" of the cause. As Lotze phrases it, things "take note of" one another's compresence in the universe, or we might say the efficient cause and that on which it exercises its efficiency are _en rapport_. "Matter" is sensitive to the presence of the "efficient cause," and in response to this sensitivity, puts forth successive determinations, expands its latent tendencies on definite lines.

The name "motion" has a wider sense for Aristotle than it has for ourselves. He includes under the one common name all the processes by which things come to be what they are or cease to be what they have been. Thus he distinguishes the following varieties of "motion": _generation_ (the coming of an individual thing into being), with its opposite _decay_ or _corruption_ (the passing of a thing out of being), _alteration_ (change of _quality_ in a thing), _augmentation_ and _diminution_ (change in the _magnitude_ of a thing), _motion through space_ (of which latter he recognises two sub-species, rectilinear _transference_ and _rotation_ in a circular orbit about an axis). It is this last variety, motion through space, which is the most fundamental of all, since its occurrence is involved in that of any of the other types of process mentioned, though Aristotle does not hold the thorough-going mechanical view that the other processes are only apparent, and that, as we should put it, qualitative change is a mere disguise which mechanical motion wears for our senses.

*The Eternity of Motion*.--Certain very important consequences follow from the conception of efficient causation which we have been describing. Aristotle has no sympathy with the "evolutionist" views which had been favoured by some of his predecessors. According to his theory of organic generation, "it takes a man to beget a man "; where there is a baby, there must have been a father. Biological kinds representing real clefts in Nature, the process of the production of a young generation by an already adult generation must be thought of as without beginning and without end. There can be no natural "evolution" of animals of one species from individuals of a different kind. Nor does it occur to Aristotle to take into account the possibility of "Creationism," the sudden coming into being of a fully fledged first generation at a stroke. This possibility is excluded by the doctrine that the "matter" of a thing must exist beforehand as an indispensable condition of the production of that thing. Every baby, as we said, must have had a father, but that father must also have been a baby before he was a full-grown man. Hence the perpetuation of unchanging species must be without beginning and without end. And it is implied that all the various processes, within and without the organism, apart from which its life could not be kept up, must be equally without beginning and without end. The "cosmos," or orderly world of natural processes, is strictly "eternal"; "motion" is everlasting and continuous, or unbroken. Even the great Christian theologians who built upon Aristotle could not absolutely break with him on this point. St. Thomas, though obliged to admit that the world was actually created a few thousand years before his own time, maintains that this can only be known to be true from revelation, philosophically it is equably tenable that the world should have been "created from all eternity." And it is the general doctrine of scholasticism that the expression "creation" only denotes the absolute dependence of the world on God for its being. When we say "God created the world out of nothing," we mean that He did not make it out of pre-existing matter, that it depends for its being on Him only; the expression is purely negative in its import.

*God*.--With the doctrine of the eternity of the world and the processes which make up its life we come close to the culminating theory of Aristotelian First Philosophy, its doctrine of God, as the eternal, unchanging source of all change, movement, and process. All motion is a process within matter by which the forms latent in it are brought into actual manifestation. And the process only takes place in the presence of an adequate efficient cause or source of motion. Hence the eternity of natural processes involves the existence of one or more eternal sources of motion. For, if we do not admit the existence of an unoriginated and ever-present source or sources of motion, our only alternative is to hold that the world-process is due to a series of sources of motion existing successively. But such a view would leave the unity and unbroken continuity of the world-process unaccounted for. It would give us a succession of processes, temporally contiguous, not one unbroken process. Hence we argue from the continuity of motion to its dependence on a source or sources which are permanent and present throughout the whole everlasting world-process. And when we come to the question whether there is only one such ultimate source of movement for the whole universe, or several, Aristotle's answer is that the supreme "Unmoved Mover" is one. One is enough for the purpose, and the law of parcimony forbids us to assume the superfluous. This then is the Aristotelian conception of God and God's relation to the world. God is the one supreme unchanging being to whose presence the world responds with the whole process of cosmic development, the ultimate educer of the series of "forms" latent in the "matter" of the world into actual manifestation. Standing, as He does, outside the whole process which by His mere presence He initiates in Nature, He is not himself a composite of "form" and "matter," as the products of development are. He is a pure individual "form" or "actuality," with no history of gradual development behind it. Thus He is a purely immaterial being, indispensable to the world's existence but transcending it and standing outside it. _How_ His presence inspires the world to move Aristotle tries to explain by the metaphor of appetition. Just as the good I desire and conceive, without itself "moving" "moves" my appetition, so God moves the universe by being its good. This directly brings about a uniform unbroken rotation of the whole universe round its axis (in fact, the alternation of day and night). And since this rotation is communicated from the outermost "sphere" of heaven to all the lesser "spheres" between it and the immovable centre, the effects of God's presence are felt universally. At the same time, we must note that though God is the supreme Mover of the Universe, He is not regarded by Aristotle as its Creator, even in the sense in which creation can be reconciled with the eternity of the world. For the effect of God's presence is simply to lead to the development of "form" in an already existing "matter." Without God there could be no "form" or order in things, not even as much as is implied in the differentiation of matter into the four "elements," yet "primary matter" is no less than God a precondition of all that happens.

It is characteristic of Aristotle that his God is as far from discharging the functions of a Providence as He is from being a Creator. His "activity" is not, as Plato had made it, that of the great "Shepherd of the sheep." As far as the world is concerned, God's only function is to be there to move its appetition. For the rest, the unbroken activity of this life is directed wholly inward. Aristotle expressly calls it an "activity of immobility." More precisely, he tells us, it is activity of thought, exercised unbrokenly and everlastingly upon the only object adequate to exercise God's contemplation, Himself. His life is one of everlasting _self_-contemplation or "thinking of thought itself." Like all unimpeded exercise of activity, it is attended by pleasure, and as the activity is continuous, so the pleasure of it is continuous too. At our best, when we give ourselves up to the pure contemplative activity of scientific thought or aesthetic appreciation, we enter for a while into this divine life and share the happiness of God. But that is a theme for our chapter on the _Ethics_.

It is a far cry from this conception of a God untroubled by care for a world to which He is only related as the object of its aspiration to the God who cares even for the fall of the sparrow and of whom it is written, _Sic Deus dilexit mundum_, but it was the standing task of the philosophical theologians of the Middle Ages to fuse the two conceptions. Plato's God, who, if not quite the Creator, is the "Father and Fashioner" of us all, and keeps providential watch over the world He has fashioned, would have lent Himself better to their purposes, but Plato was held by the mediaeval church to have denied the resurrection of the body. The combination of Aristotle's Theism with the Theism of early Christianity was effected by exquisitely subtle logical devices, but even in St. Thomas one cannot help seeing the seams.

Nor can one help seeing in Aristotle's own doctrine the usual want of coherence between an initial anti-Platonic bias and a final reversion to the very Platonic positions Aristotle is fond of impugning. We are told at the outset that the Platonic "separate forms" are empty names, and that the real individual thing is always a composite of matter and a form which only exists "in matter." We find in the end that the source of the whole process by which "matter" becomes imbued with "form" is a being which is "pure" form and stands outside the whole development which its presence sets up. And the issue of Aristotle's warning against "poetic metaphors" is the doctrine that God moves the world by being "the object of the world's desire."

*CHAPTER IV*

*PHYSICS*

There is no part of Aristotle's system which has been more carefully thought out than his Physics; at the same time it is almost wholly on account of his physical doctrines that his long ascendancy over thought is so much to be regretted. Aristotle's qualifications as a man of science have been much overrated. In one department, that of descriptive natural history, he shows himself a master of minute and careful observation who could obtain unqualified praise from so great a naturalist as Darwin. But in Astronomy and Physics proper his inferiority in mathematical thinking and his dislike for mechanical ways of explaining facts put him at a great disadvantage, as compared with Plato and Plato's Pythagorean friends. Thus his authority was for centuries one of the chief influences which prevented the development of Astronomy on right lines. Plato had himself both taught the mobility of the earth and denied correctly that the earth is at the centre of the universe, and the "Copernican" hypothesis in Astronomy probably originated in the Academy. Aristotle, however, insists on the central position of the earth, and violently attacks Plato for believing in its motion. It is equally serious that he insists on treating the so-called "four elements" as ultimately unanalysable forms of matter, though Plato had not only observed that so far from being the ABC (_stoicheia_ or _elementa_, literally, letters of the alphabet) of Nature they do not deserve to be called even "syllables," but had also definitely put forward the view that it is the geometrical structure of the "corpuscles" of body upon which sensible qualities depend. It is on this doctrine, of course, that all mathematical physics rests. Aristotle reverts to the older theory that the differences between one "element" and another are qualitative differences of a sensible kind. Even in the biological sciences Aristotle shows an unfortunate proneness to disregard established fact when it conflicts with the theories for which he has a personal liking. Thus, though the importance of the brain as the central organ of the sensori-motor system had been discovered in the late sixth or early fifth century by the physician Alemacon of Crotona, and taught by the great Hippocrates in the fifth and by Plato in the fourth century, Aristotle's prejudices in favour of the doctrines of a different school of biologists led him to revert to the view that it is the heart which is the centre of what we now call the "nervous system." It is mainly on account of these reactionary scientific views that he was attacked in the early seventeenth century by writers like our own Francis Bacon, who found in veneration for Aristotle one of the chief hindrances to the free development of natural science. The same complaints had been made long before by critics belonging to the Platonic Academy. It is a Platonist of the time of Marcus Aurelius who sums up a vigorous attack on the Aristotelian astronomy by the remark that Aristotle never understood that the true task of the physicist is not to prescribe laws to Nature, but to learn from observation of the facts what the laws followed by Nature are.

In determining the scope of Physics, we have to begin by considering what is the special characteristic of things produced by Nature as contrasted with those produced by "art." The obvious distinction, intimated by the very etymology of the word "Nature" (_physis_, connected with _phyesthai_, to grow, to be born, as _natura_ is with _nasci_), is that "what is by Nature" is born and grows, whereas what is as a result of artifice is _made_. The "natural" may thus be said to consist of living bodies and of their constituent parts. Hence inorganic matter also is included in "Nature," on the ground that living tissue can be analysed back into compounds of the "elements." Now things which are alive and grow are distinguished from things which are made by "a source of motion and quiescence within themselves"; all of them exhibit motions, changes of quality, processes of growth and decline which are initiated from within. Hence Nature may be defined as the totality of things which have a source of motion internal to themselves and of the constituent parts of such things. Nature then comprises all beings capable of spontaneous change. Whatever either does not change at all, or only changes in consequence of external influences, is excluded from Nature.

Thus the fundamental fact everywhere present in Nature is "change," "process," "motion." Since motion in the literal sense of change of position is involved as a condition of every such process, and such motion requires space through which to move and time to move in, the doctrine of space and time will also form part of Physics. Hence a great part of Aristotle's special lectures on Physics is occupied with discussion of the nature of space and time, and of the continuity which we must ascribe to them if the "continuous motion" on which the unbroken life of the universe depends is to be real Aristotle knows nothing of the modern questions whether space and time are "real" or only "phenomenal," whether they are "objective" or "subjective." Just as he simply assumes that bodies are things that really exist, whether we happen to perceive them or not, so he assumes that the space and time in which they move are real features of a world that does not depend for its existence on our perceiving it.

His treatment of space is singularly _naif_. He conceives it as a sort of vessel, into which you can pour different liquids. Just as the same pot may hold first wine and then water, so, if you can say, "there was water here, but now there is air here," this implies the existence of a receptacle which once held the water, but now holds the air. Hence a jug or pot may be called a "place that can be carried about," and space or place may be called "an immovable vessel." Hence the "place" of a thing may be defined as the boundary, or inner surface, of the body which immediately surrounds the thing. It follows from this that there can be no empty space. In the last resort, "absolute space" is the actual surface of the outermost "heaven" which contains everything else in itself but is not contained in any remoter body. Thus all things whatever are "in" this "heaven." But it is not itself "in" anything else. In accord with the standing Greek identification of determinate character with limitation, Aristotle holds that this outermost heaven must be at a limited distance from us. Actual space is thus finite in the sense that the volume of the universe could be expressed as a finite number of cubic miles or yards, though, since it must be "continuous," it is infinitely divisible. However often you subdivide a length, an area, or a volume, you will always be dividing it into lesser lengths, &c., which can once more be divided. You will never by division come to "points," _i.e._ mere positions without magnitude of divisibility.