The difference between the past and present selves of the same individual is so great as to make them different persons for all moral purposes. That single fact we were just speaking of—the fact that no man would care for vengeance on one who had injured him, provided he knew that all memory of the offence had been blotted utterly from his enemy's mind—proves the entire proposition. It shows that it is not the present self of his enemy that the avenger is angry with at all, but the past self. Even in the blindness of his wrath he intuitively recognizes the distinction between the two.

Ch. 11. - Dr. Heidenhoff's Process (1880)