people--which is, in a certain sense, also a man--can a change be
demanded which breaks the unity and continuity of the person. A man can
change greatly, almost completely even, but the change must take place
within his continuity.

It is true that in certain individuals there occur what are called
changes of personality; but these are pathological cases, and as such
are studied by alienists. In these changes of personality, memory, the
basis of consciousness, is completely destroyed, and all that is left to
the sufferer as the substratum of his individual continuity, which has
now ceased to be personal, is the physical organism. For the subject who
suffers it, such an infirmity is equivalent to death--it is not
equivalent to death only for those who expect to inherit his fortune, if
he possesses one! And this infirmity is nothing less than a revolution,
a veritable revolution.

A disease is, in a certain sense, an organic dissociation; it is a
rebellion of some element or organ of the living body which breaks the
vital synergy and seeks an end distinct from that which the other
elements co-ordinated with it seek. Its end, considered in itself--that
is to say, in the abstract--may be more elevated, more noble, more
anything you like; but it is different. To fly and breathe in the air
may be better than to swim and breathe in the water; but if the fins of
a fish aimed at converting themselves into wings, the fish, as a fish,
would perish. And it is useless to say that it would end by becoming a
bird, if in this becoming there was not a process of continuity. I do
not precisely know, but perhaps it may be possible for a fish to
engender a bird, or another fish more akin to a bird than itself; but a
fish, this fish, cannot itself and during its own lifetime become a
bird.