The _identity_, which we are to consider, is, as I have already said, the identity only of the principle which feels and thinks, without regard to the changeable state of the particles of the brain, or of the body in general. This unity and permanence of the principle, which thinks, if we had still to invent a phrase, I would rather call _mental_ identity, than _personal_ identity, though the latter phrase may now be considered as almost fixed by the general use of philosophers. On no system can there be this absolute identity, unless as strictly mental; for, if we adopt the system of materialism, we must reject the absolute lasting identity of the thinking principle altogether; and if we do not adopt that system, it is in the _mind_ alone that we must conceive the identity to subsist. The _person_, in the common and familiar meaning of the term, though involving the mind, is yet more than the mere mind; and, by those, at least, who are not conversant with the writings of philosophers on the subject, sameness of person would be understood as not _mental_ only, but as combining with the absolute identity of the mind, some sort of identity of the body also; though, it must be confessed, that, in its application to the body, the term _identity_ is not used with the same strictness, as in its application to the mind; the bodily identity being not absolute, but admitting of considerable, and ultimately, perhaps, even of total, change, provided only the change be so gradual, as not to be inconsistent with apparent continuity of existence. Still, however, identity of _person_, at least in the popular notion of it, is something more than identity of mind. “All mankind,” says Dr Reid, “place their personality in something, that cannot be divided or consist of parts. A part of a person is a manifest absurdity. “When a man loses his estate, his health, his strength, he is still the same person, and has lost nothing of his personality. If he has a leg or an arm cut off, he is the same person he was before. The amputated member is no part of his person, otherwise it would have a right to a part of his estate, and be liable for a part of his engagements; it would be entitled to a share of his merit and demerit, which is manifestly absurd. A person is something indivisible, and is what Leibnitz calls a monad.”[45]