This consideration is of itself decisive of the question of _identity_; since, if it be manifest, that there is an universal, immediate, and irresistible impression of our identity,--an impression, which cannot be traced to any law of thought more simple,--its truth is established by a species of evidence, which must be allowed to be valid, before the very objections can be put, in which it is professedly denied;--every objection, however sceptical, involving, as we have seen, and necessarily involving, the assertion of some such intuitive proposition, from which alone its authority, if it have any authority, is derived. In endeavouring to move the whole world of truth with his lever, there must still be some little spot at least, on which the sceptic must be content to rest his foot as firmly as others. Δὸς ποῦ στῶ, he must still be condemned to say with Archimedes; and if we allow no resting-place to his foot,--or, even allowing him this, if we allow no fulcrum for the instrument which he uses, he may contract or lengthen his lever at pleasure; but all the efforts, which in such circumstances, he can make, will exhibit nothing so striking to those by whom the efforts are witnessed, as the laborious impotence of him who employs them. To deny any first principles of intuitive belief, that are not themselves to stand in need of a demonstration,--which, as a demonstration, or series of consecutive propositions, can be founded, in its primary evidence, only on some principle of the same kind,--is, indeed, for such a sceptical mechanic, to set his foot upon air, rather than on the ground, on which all around him are standing, and to throw away the single fulcrum on which his lever rests, and from which alone all its power is derived. The belief of our mental identity, then, we may safely conclude, is founded on an essential principle of our constitution,--in consequence of which, it is _impossible_ for us to consider our _successive_ feelings, without regarding them as truly _our_ successive feelings--states, or affections of one thinking substance. But though the belief of the identity of the substance which thinks, is thus established on the firmest of all grounds, the very ground, as we have seen, on which demonstration itself is founded,--even though no particular fallacy could be traced in the objections brought against it, which I detailed in my last Lecture,--it is still an interesting inquiry, in what the fallacy of the objections consists; and the inquiry is the more interesting, as it will lead us to some remarks and distinctions, which, I flatter myself, will throw some light on the philosophy of all the changes, material as well as mental, that are every moment taking place in the universe.