As plainly then as one half of Descartes' philosophy is materialistic, so plainly, that half, instead of a necessary outgrowth and exact correlative of the other or idealistic moiety is, on the contrary, the latter's diametrical and implacable opponent. As plainly, therefore, as the one is true, must the other be false, and Cartesian idealism, in so far as its character has been exhibited above, has, I submit, been demonstrated to be true. The greater the pity that it was not brought to maturity by its author. In enumerating its first principles, Descartes, as I must once again observe, was forming a logical basis whereon a comprehensive and consistent conception of an external universe might forthwith have been securely deposited, had he not unluckily, instead of himself proceeding to build on his own foundations, with congruous materials, left them free for others to build upon with gold, silver, precious stones, wood, hay, or stubble, as chance might determine. May I, without presumption, hazard a conjecture as to the sort of fabric that might have arisen, if he had steadily prosecuted his original design? At the stage which we are supposing him to have reached, very little remained to complete the work. Around man, around every individual man, or other conscious intelligence, as its centre, is ranged infinitely extended space, filled with, or, as it were, composed of various kinds of matter, every kind and every separate portion of which is endowed with special qualities capable of communicating corresponding sensations to the central intelligence. So far all that can be predicated of any material object or portion of matter is that it is a collection of qualities; but from hence we may advance boldly to the further negative discovery that it is nothing else; that there is not and cannot be, in addition to those qualities, any substance in or to which the qualities inhere, or are in any way attached.