contradicting itself, contradicts not less flatly a twin system of unimpeachable veracity. Truth cannot be opposed to truth:--a doctrine cannot be true, even though propounded by Descartes and Huxley, if it conflict irreconcileably with doctrines which Descartes and Huxley have unanswerably demonstrated. Now one-half of Cartesian philosophy shows conclusively that amidst the countless infinity of human notions, the one single and solitary certainty of independent and self-evident authority is the existence of thought, and nothing else whatever, therefore, can be entitled to be regarded as absolutely certain which cannot be shown to rest mediately or immediately upon this. One thing which can, by strictest logical process, be shown so to rest, is the existence of a thinking self; and another is the existence of a non-self or external universe; but of this external universe we know scarcely anything beyond the bare fact that it exists. We know that outside the thinking self there are potentialities capable of somehow or other communicating sensations to the thinking self; but of the nature of these potentialities our senses teach us absolutely nothing, and the few particulars that reason is able to discover, are, with one single though very momentous exception, to which we are rapidly approaching, purely negative. We do know to a certain extent what qualities of objects are not. We know that they are not and cannot be in the least like the sensations which we call by the same names. We know that what we call the whiteness and coldness of snow or the hardness and weight of marble, can no more resemble the feelings we receive from looking at or handling snow or marble than the mental exaltation produced within us on hearing one of Bach's fugues is like the organ on which, or the organist by whom, it is played. We know that of the pictures which our senses form for us not one can possibly be a correct likeness. We know that what we fancy we see in matter we do not see; that what we seem to feel we do not feel; that the apparent structure and composition of matter cannot therefore possibly be real. To this conviction we are irresistibly drawn by a chain of idealistic reasoning of which Descartes forged the first link, and every link of which will stand the severest strain. But if this be the teaching of an idealism occupying as its base the only morsel of solid ground to be found in the mental universe, what scrap of footing is there left for an antagonistic materialism purporting to rest on what we can see and feel of a structure and composition which, as we have just satisfied ourselves, we cannot see or feel at all?