" In seven years, thought Laurie, every cell in one's body has been replaced, even our memories live in a new brain. That is not the face I saw, and these are not the eyes I saw with. Even our selves are not the same, but only a consequence of the selves we had then. Yet I was there and I am here; and this man, who is sometimes what I remember and sometimes a stranger I met at a party the other day, is also to himself the I who was there: his mind in its different skull has travelled back to a place his living feet never visited; and the pain he felt then he can feel again. "

― Mary Renault , The Charioteer