Q.E.D.
Note .-- The extent to which such causes can injure or be of service to the mind will be explained in the Fifth Part.

But I would here remark that I consider that a body undergoes death, when the proportion of motion and rest which obtained mutually among its several parts is changed.

For I do not venture to deny that a human body, while keeping the circulation of the blood and other properties, wherein the life of a body is thought to consist, may none the less be changed into another nature totally different from its own.

There is no reason, which compels me to maintain that a body does not die, unless it becomes a corpse; nay, experience would seem to point to the opposite conclusion.
It sometimes happens, that a man undergoes such changes, that I should hardly call him the same.

As I have heard tell of a certain Spanish poet, who had been seized with sickness, and though he recovered therefrom yet remained so oblivious of his past life, that he would not believe the plays and tragedies he had written to be his own: indeed, he might have been taken for a grown--up child, if he had also forgotten his native tongue.