are certain leads us back, when we consider its concrete contents, to the necessary pre-supposition on which our ideas depend, the ultimate totality in which they are all reconciled, the permanent cause on which they and we as conscious beings depend. We have therefore, says Descartes, the idea of an infinite, perfect, and all powerful being which cannot be the creation of ourselves, and must be given by some being who really possesses all that we in idea attribute to him. Such a being he identifies with God. But the ordinary idea of God can scarcely be identified with such a conception. " The majority of men," he says himself, " do not think of God as an infinite and incom prehensible being, and as the sole author from whom all things depend ; they go no further than the letters of his name." 1 " The vulgar almost imagine him as a finite thing." The God of Descartes is not merely the creator of the material universe ; he is also the father of all truth in the intellectual world. "The metaphysical truths," he says, " styled eternal have been established by God, and, like the rest of his creatures, depend entirely upon him. To say that these truths are independent of him is to speak of God as a Jupiter or a Saturn, to subject him to Styx and the Fates." 2 The laws of thought, the truths of number, are the decrees of God. The expression is anthropomorphic, no less than the dogma of material creation ; but it is an attempt to affirm the unity of the intellectual and the material world. Descartes establishes a philosophic monotheism, by which the mediaeval poly theism of substantial forms, essences, and eternal truths fades away before God, who is the ruler of the intellectual world no less than of the kingdom of nature and of grace. To attach a clear and definite meaning to the Cartesian doctrine of God, to show how much of it comes from the Christian theology and how much from the logic of idealism, how far the conception of a personal being as creator and preserver mingles with the pantheistic conception of an infinite and perfect something which is all in all, would be to go beyond Descartes and to ask for a solution of difficulties of which he was scarcely aware. It seems impossible to deny that the tendency of his principles and his arguments is mainly in the line of a metaphysical absolute, as the necessary completion and foundation of all being and knowledge. Through the truthfulness of that God as the author of all truth he derives a guarantee for our perceptions in so far as these are clear and distinct. And it is in guaranteeing the veracity of our clear and distinct conceptions that the value of his deduction of God seems in his own estimate to rest. All conceptions which do not possess these two attributes of being vivid in themselves and discriminated from all others cannot be true. But the larger part of our conceptions are in such a predicament. We think of things not in the abstract elements of the things themselves, but in connection with, and in language which presupposes, other things. Our idea of body, e.g., involves colour and weight, and yet when we try to think carefully, and without assuming anything, we find that we cannot attach any distinct idea to these terms when applied to body. In truth therefore these attributes do not belong to body at all ; and if we go on in the same way testing the received qualities of matter, we shall find that in the last resort we understand nothing by it but extension, with the secondary and derivative characters of divisibility and mobility. But it would again be useless to ask how extension as the characteristic attribute of matter is related to mind which thinks, and how God is to be regarded in reference to extension. The force of the universe is swept up and gathered in God, who communicates motion to the parts of 1 (Euvres, vi. 132. a (Euvres, vi. 109. extension, and sustains that motion from moment to moment ; and in the same way the force of mind has really been concentrated in God. Every moment one expects to find Descartes saying with Hobbes that man s thought has created God, or with Spinoza and Malebranche that it is God who really thinks in the apparent thought of man. After all, the metaphysical theology of Descartes, however essential in his own eyes, serves chiefly as the ground for constructing his theory of man and of the universe. His fundamental hypothesis relegates to God all forces in their ultimate origin. Hence the world is left open for the free play of mechanics and geometry. The disturbing conditions of will, life, and organic forces are eliminated from the problem ; he starts with the clear and distinct idea of extension, figured and moved, and thence by mathematical laws he gives a hypothetical explanation of all things. Such explanation of physical phenomena is the main problem of Descartes, and it goes on encroaching upon territories once supposed proper to the mind. Descartes began with the certainty that we are thinking beings ; that region remains untouched ; but up to its very borders the mechanical explanation of nature reigns unchecked. The physical theory, in its earlier form in the World, and in its later in the Principles of Philosophy (which the present account follows), rests upon the metaphysical conclusions of the Meditations. It proposes to set forth the genesis of the existing universe from principles which can be plainly understood, and according to the acknow ledged laws of the transmission of movement. The idea of force is one of those obscure conceptions which originate in an obscure region, in the sense of muscular power. The true physical conception is motion, the ultimate ground of which is to be sought in God s infinite power. Accordingly the quantity of movement in the universe, like its mover, can neither increase nor diminish. The only circumstance which physics has to consider is the transference of move ment from one particle to another, and the change of its direction. Man himself cannot increase the sum of motion ; he can only alter its direction. The whole conception of force may disappear from a theory of the universe ; and we can adopt a geometrical definition of motion as the shifting of one body from the neighbourhood of those bodies which immediately touch it, and which are assumed to be at rest, to the neighbourhood of other bodies. Motion, in short, is strictly locomotion, and nothing else. Descartes has laid down three laws of nature, and seven secondary laws regarding impact. The latter are to a large extent incorrect. The first law affirms that every body, so far as it is altogether unaffected by extraneous causes, always perseveres in the same state of motion or of rest ; and the second law that simple or elementary motion is always in a straight line. 3 These doctrines of inertia, and of the composite character of curvilinear motion, were scarcely apprehended even by Kepler or Galileo ; but they follow naturally from the geometrical analysis of Descartes, Extended body has no limits to its extent, though the power of God has divided it in lines discriminating its parts in endless ways. The infinite universe is infinitely full of matter. Empty space, as distinguished from material extension, is a fictitious abstraction. There is no such thing really as a vacuum, any more than there are atoms or ultimate indivisible particles. In both these doctrines of a priori science Descartes has not been subverted, but, if anything, corroborated by the results of experimental physics for the so-called atoms of chemical theory already presuppose, from the Cartesian point of view, certain aggregations of the primitive particles of matter. Descartes regards matter as uniform in character 3 Princip., pt. ii. 37.
