"The whole of this doctrine leads us to a conclusion which is of great importance in the present affair, viz. that all the nice and subtle questions concerning personal identity can never possibly be decided, and are to be regarded rather as grammatical than as philosophical difficulties. Identity depends on the relations of ideas, and these relations produce identity by means of that easy transition they occasion. But as the relations, and the easiness of the transition may diminish by insensible degrees, we have no just standard by which we can decide any dispute concerning the time when they acquire or lose a title to the name of identity. All the disputes concerning the identity of connected objects are merely verbal, except so far as the relation of parts gives rise to some fiction or imaginary principle of union, as we have already observed. "What I have said concerning the first origin and uncertainty of our notion of identity, as applied to the human mind may be extended, with little or no variation, to that of _simplicity_. An object, whose different co-existent parts are bound together by a close relation, operates upon the imagination after much the same manner as one perfectly simple and undivisible, and requires not a much greater stretch of thought in order to its conception. From this similarity of operation we attribute a simplicity to it, and feign a principle of union as the support of this simplicity, and the centre of all the different parts and qualities of the object."--(I. pp. 331-3.) The final result of Hume's reasoning comes to this: As we use the name of body for the sum of the phenomena which make up our corporeal existence, so we employ the name of soul for the sum of the phenomena which constitute our mental existence; and we have no more reason, in the latter case, than in the former, to suppose that there is anything beyond the phenomena which answers to the name. In the case of the soul, as in that of the body, the idea of substance is a mere fiction of the imagination. This conclusion is nothing but a rigorous application of Berkeley's reasoning concerning matter to mind, and it is fully adopted by Kant.[35] Having arrived at the conclusion that the conception of a soul, as a substantive thing, is a mere figment of the imagination; and that, whether it exists or not, we can by no possibility know anything about it, the inquiry as to the durability of the soul may seem superfluous.