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Having demonstrated the existence of God, he had to prove the distinction between body and soul. This, to him, was easy. The fundamental attribute of substance must be extension, because we can abstract from substance all the qualities except extension. The fundamental attribute of mind is thought, because by this attribute mind is revealed to itself. Now, according to one of his logical axioms, two substances are really distinct when their ideas are complete, and in no way imply each other. The ideas, therefore, of extension and thought being distinct, it follows that substance and mind are distinct in essence.

We need not pursue our analysis of his metaphysical notions further. We only stop to remark on the nature of his demonstrations of God and the soul. It is, and was, usual to prove the existence of God from what is called the "evidence of design," from the world, in fact. Descartes neither started from design nor from motion, which must have a mover: he started from the à priori ideas of perfection and infinity; his proof was in the clearness of his idea of God-in an analysis of his own mind. His method was that of definition and deduction. To define the idea of God, and hence to construct the world-not to contemplate the world, and hence infer the existence of Godwas the route he pursued. Is it not eminently the procedure of a mathematician? and of a mathematician who has taken consciousness as his startingpoint?

Descartes' speculations are beautiful exemplifications of his method; and he follows that method, even when it leads him to the wildest conclusions.

His physical speculations are sometimes admirable (he made some important discoveries in optics), but mostly fanciful. The famous theory of vortices deserves a mention here as an example of his method.

He begins by banishing the notion of a vacuum, not, as his contemporaries said, because Nature has a horror of a vacuum, but because the essence of substance being extension, wherever there is extension there is substance, consequently empty space is a chimera. The substance which fills all space must be assumed as divided into equal angular parts. Why must this be assumed?-Because it is the most simple, therefore the most natural supposition. This substance being set in motion, the parts are ground into a spherical form; and the corners thus rubbed off, like filings or sawdust, form a second and more subtle kind of substance. There is, besides, a third kind of substance, coarser and less fitted for motion. The first kind makes luminous bodies, such as the sun and fixed stars; the second kind makes the transparent substance of the skies; the third kind is the material of opaque bodies, such as earth, planets, &c. We may also assume that the motions of these parts take the form of revolving circular currents, or vortices. By this means the matter will be collected to the centre of each vortex, while the second or subtle matter surrounds it, and by its centrifugal effort constitutes light. The planets are carried round the sun by the motion of this vortex, each planet being at such a distance from the sun as to be in a part of the vortex suitable to its solidity and mobility. The motions are pre

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vented from being exactly circular and regular by various causes. For instance, a vortex may be pressed into an oval shape by contiguous vortices.*

Descartes, in his physics, adopted a method which permitted him to set aside the real qualities and the substantial forms (which others were seeking), and to consider only the relations of number, figure, and motion. In a word, he saw in physics only mathematical problems. This was premature. Science, in its infancy, cannot be carried on by the deductive method alone: that is reserved for the

maturity of science. Descartes was unaware of that, and failed in consequence.

But this deductive method, though premature, was puissant. Science must employ it, and Bacon's greatest error was in not sufficiently acknowledging it. Hence we may partly account for the curious fact that Bacon, with his cautious method, made no discoveries, while Descartes, with his rash method, made important discoveries. Of course the greater physical knowledge of Descartes, and the greater attention bestowed by him upon physics, had something to do with this; but his method also assisted him, because his discoveries were of a kind to which the mathematical method was strictly applicable.

That Descartes had read Bacon there is no doubt. He has himself praised Bacon's works as leaving nothing to be desired on the subject of experience;

We have followed Dr. Whewell's exposition of this theory, as given by him- Hist. of Ind. Sciences,' ii. p. 134. The curious reader will do well, however, to turn to Descartes' own exposition, where it is illustrated by diagramsPrincipia Philosophiæ.'

but he perceived Bacon's deficiency, and declared that we are liable to collect many superfluous experiences of particulars, and not only superfluous but false, if we have not ascertained the truth before we make these experiences. In other words, experience should be the verification of an à priori conception; whereas Bacon teaches us to form our conceptions from experience.

We have said enough to make the method of Descartes appreciable. His position is that of founder of the deductive method on the basis of Consciousness. His scholars may be divided into the mathematical cultivators of physics, and the deductive cultivators of philosophy. By the first he was speedily surpassed, and his influence on them can only be regarded as an impulsion. By the second he was continued: his principles were unhesitatingly accepted, and only developed in a somewhat different manner.

His philosophical method subsists in the present day. It is the method implicitly or explicitly adopted by most metaphysicians in their speculations upon ontological subjects. Is it a good method? The question is of the highest importance: we shall endeavour in the next chapter to answer it.

CHAPTER IV.

IS THE METHOD TRUE?

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IN the dedicatory epistle prefixed to his Meditations' Descartes declares that his demonstrations of the existence of God, &c., " equal, or even surpass, in certitude the demonstrations of geometry." Upon what does he found this belief? He founds it upon the very nature of certitude as conceived by him.

true.

What is the basis of all certitude? Consciousness. Whatever I am distinctly conscious of, I must be certain of; all the ideas which I find in my consciousness, as distinctly conceived, must be The belief I have in my existence is derived from the fact of my consciousness: I think, therefore I exist. Now as soon as we think we conceive a truth with distinctness, we are irresistibly led to believe in it; and if that belief is so firm that we can never have any reason to doubt that which we believe, we have all the certitude that can be desired.

Further we have no knowledge whatever of anything external to us, except through the medium of ideas. What is the consequence? The consequence is, says Descartes, that whatever we find in the ideas must necessarily be in the external things.

It is only in our minds that we can seek whether

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