It is to be traced chiefly, I conceive, to a source which is certainly the most abundant source of error in the writings and silent reflections of philosophers, especially of those who are gifted with originality of thought,--the ambiguity of the language they use, when they retain a word with one meaning, which is generally understood in a different sense; the common meaning, in the course of their speculations, often mingling insensibly with their own, and thus producing a sort of confusion, which incapacitates them from perceiving the precise consequences of either. Mr Locke gives his own definition of the word person, as comprised in the very consciousness which he supposes to be all that is essential to personal identity; or at least he speaks of consciousness so vaguely and indefinitely, as to allow this meaning of his definition to be present to his own mind, as often as he thought of personality. “To find,” he says, “wherein personal identity consists, we must consider what _person_ stands for; which, I think, is a thinking intelligent being, that has reason and reflection, and can consider itself as itself, the same thinking thing, in different times and places, which it does only by that consciousness, which is inseparable from thinking.”[53] Having once given this definition of a person, there can be no question, that personal identity, in _his_ sense, is wherever _consciousness_ is, and only where consciousness is. But this is true of a person, only as defined by him; and, if strictly analysed, means nothing more, than that consciousness is wherever consciousness is,--a doctrine, on which, certainly, he could not have thought it worth his while to give any very long commentary. It appears more important however, even to himself, and worthy of the long commentary which he has given it, because, in truth, he cannot refrain from still keeping, in his own mind, some obscure impression of the more common meaning of the term, and extending to a _person_, as thus commonly understood, what is true only of a person, as defined by him. It is as if some whimsical naturalist should give a definition of the word _animal_, exclusive of every winged creature, and should then think that he was propounding a very notable and subtile paradox, in affirming that no animal is capable of rising for a few minutes above the surface of the earth. It would be a paradox, only inasmuch as it might suggest to those who heard it, a meaning _different_ from that of the definition; and, but for this misconception, which the author of it himself might share, would be so insignificant a truism, as not to deserve even the humblest of all praise, that of amusing absurdity.