particular, when saying, as he somewhere does, that 'all we are conscious of is a series of perceptions,' denies and affirms it at one and the same time. For how can there be perception without a percipient? or how consciousness without a conscious entity? or how can that entity be conscious of feeling without being simultaneously conscious that it is itself which feels, without knowing, consequently, that it has a self, or without being warranted, if it possess the gift of speech, in declaring, in words even more emphatic than those of Descartes, 'I _myself_ am'? And how, if these questions do not admit of reply, can Professor Huxley be warranted in declaring self and non-self to be mere 'hypotheses by which we account for the facts of consciousness,' and adding that of their existence we 'neither have, nor by any possibility can have' the same 'unquestionable and immediate certainty as we have of the states of consciousness which we consider to be their effects'? Surely the existence of self is one of the most direct and immediate subjects of consciousness; yet it does not depend for evidence on consciousness alone, but is as unanswerably demonstrable as that two straight lines cannot enclose space or that parallel lines cannot meet, or as any other mathematical negation. No ratiocinative deduction can be more incontestable than that, since _I_ have thoughts, there must be an _I_ to have them. Whoever thus assures himself of the existence of self obtains simultaneously equal assurance of the existence of non-self; for feeling that his conscious self is not boundless, but is confined within limits, he cannot doubt that beyond those limits there must be space, and, receiving continual sensations from without, he perceives that there are, in external space, potentialities of imparting sensations. Thus, I repeat, Descartes in laying down the first principles of his philosophy created an intellectual basis for the external universe. Unfortunately, however, instead of proceeding to place its proper superstructure on the foundation thus laid, he wilfully stepped aside from what he had just pronounced the only firm ground in existence, and undertook to raise a rival edifice on part of the formless void beyond. Deeply struck by the grand discoveries of his illustrious contemporaries, Galileo and Harvey, and thence discovering for himself that the phenomena of remotest worlds and also the involuntary phenomena of our own bodily frames take place in accordance with forces of uniform operation, he leaped suddenly to the conclusion that those forces are purely mechanical. The circulation of the blood, he says, 'is as much the necessary result of the structure of the parts one can see in the heart, and of the heat which one may feel there, and of the nature of the blood which may be experimentally ascertained, as is the motion of a clock the result of the force, situation, and figure of its wheels and of its weight.' Nor, in his