from its own essential attribute. Accordingly, in his physical philosophy, Des Cartes attempts to explain every thing on mechanical principles, starting with the hypothesis that a certain quantity of motion has been impressed on the material universe by God at the first, a quantity which can never be lost or diminished, and that space is an absolute plenum in which motion propagates itself in circles. It is unnecessary to follow Des Cartes into the detail of the theory of vortices. It is more to the puqjose to notice the nature of the reasons by which he is driven to regard such a mechanical explanation of the universe as necessary. A real or substantive existence is, in his view, a res com- pleta, a thing that can be conceived as a whole in itself without relations to any other thing. Now matter and mind are, he thinks, such complete existences, so long as we conceive them, as pure intelligence mast conceive them, as abstract opposites of each other ; and do not permit ourselves to be confused by those mixed modes of thought which are due to sense or imagination, Des Cartes does not see that in this very abstract opposition there is a bond of union between mind and matter, that they are correlative opposites, and therefore in their separation res incomplete. In other words, they are merely elements of reality substantiated by abstract thought into independent realities. He indeed partly retracts his assertion that mind and matter severed from each other are res completes, when he declares that neither can be conceived as existing apart from God, and that therefore, strictly speaking, God alone is a substance. But as we have seen, he avoids the necessary inference that in God the opposition between mind and matter is reconciled or transcended, by conceiving God as abstract self-consciousness or will, and the material world not as his necessary manifestation, but simply as his creation, as having its origin in an act of bare volition, and that only. His God is the God of monotheism and not of Christianity, and therefore the world is to God always a foreign matter which he brings into being, and acts on
from without, but in which he is not revealed.It is a natural consequence of this view that nature is essentially dead matter, that beyond the motion it has received from God at the beginning, and which it transmits from part to part without increase or diminution, it has no principle of activity in it. Every trace of vitality in it must be explained away as a mere false reflection upon it of the nature of mind. The world is thus " cut in two with a hatchet," and there is no attraction to overcome the mutual repulsion of its severed parts. Nothing can be admitted in the material half that savours of self-deter mination, all its energy must--be communicated, not self- originated ; there is no room for gravitation, still less for magnetism or chemical affinity, in this theory. A fortiori, animal life must be completely explained away. The machine may be very complicated, but it is still, and can be nothing but, a machine. If we once admitted that matter could be anything but mechanical, we should be on the way to admit that matter could become mind. When a modern physical philosopher declares that everything, even life and thought, is ultimately reducible to matter, we cannot always be certain that he means what he seems to say. Not seldom the materialist soi-disaiU when we hear his account of the properties of matter, turns out to be something like a spiritualist in disguise; but when Des Cartes asserted that everything lift mind is material, and that the animals are automata, there is no such dubiety of interpretation. He said what he meant, and meant what he said, in the hardest sense his words can bear. His matter was not even gravitating, much less living ; it had no property except that of retaining and transmitting the motion received from without by pressure and impact. And his animals were automata, not merely in the sense of being governed by sensation and instinct, but precisely in the sense that a watch is an automaton. Henry More cries out against the ruthless consequence with which he develops his principles to this result. " In this," he says, " I do not so much admire the penetrative power of your genius as I tremble for the fate of the animals. What I recognize in you is not only subtlety of thought, but a hard and remorseless logic with which you arm yourself as with a sword of steel, to take away life and sensation with one blow, from almost the whole animal kingdom." But Des Cartes was not the man to be turned from the legitimate result of his principles by a scream. "Nee moror astutias et sagacitates canum et vulpium, nee qusecunque alia propter cibum, venerem, aut metum a brutis fiunt. Profiteor enim me posse perfacile ilia omnia ut a sola membrorum conformatione profecta explicare."[1]
The difficulty reaches its height when Des Cartes attempts to explain the union of the body and spirit in man. Between two substances which, when clearly and distinctly conceived, do not imply each other, there can be none but -an artificial unity, a unity of composition that still leaves them external to each other. Even God cannot make them one in any higher sense.[2] And as it is impossible in the nature of mind to see any reason why it should be embodied, or in the nature of matter to see any reason why it should become the organ of mind, the union of the two must be taken as a mere empirical fact. When we put on the one side all that belongs to intelligence, and on the other all that belongs to matter, there is a residuum in our ideas which we cannot reduce to either head. This residuum consists of our appetites, our passions, and our sensations, including not only tha feelings of pain and pleasure, but also the perceptions of colour, smell, taste, of hardness and softness, and all the other qualities appre hended by touch. These must be referred to the union of mind with body. They are subjective in the sense that they give us no information either as to the nature of things or of mind. Their function is only to indicate what things are useful or hurtful to our composite nature as such, or in other words what things tend to confirm or dissolve the unity of mind and body. They indicate that something is taking place in our body, or without it, and so stimulate us to some kind of action, but ichat it is that is taking place they do not tell us. There is no resem blance in the sensation of pain produced by great heat to the rending of the fibres of our body that causes it. But we do not need to know the real origin of our sensation to prevent us going too near the fire. Sensation leads us into error only when we are not conscious that its office is merely practical, and when we attempt to make objective judgments by means of its obscure and confused ideas, e.g., when we say that there is heat in our hands or in the fire. And the remedy for this error is to be found simply in the clear conviction of the subjectivity of sensation.
force us to ask how Des Cartes can consistently admit that a subjective result such as sensation, a result in mind, should be produced by matter, and on the other hand how an objective result, a result in matter, should be effected by mind. Des Cartes explains at great length, according to his modification of the physiology of the day, that the pineal gland, which is the immediate organ of the soul, is acted on by the nerves through the " animal spirits," and again by reaction upon these spirits produces motions in the body. It is an obvious remark that this explanation either materializes mind, or else puts for the solution the very problem to be solved. It was therefore in
the spirit of Des Cartes, it was only making explicit what
