Each living creature is said to be alive and to be the same individual - as for example someone is said to be the same person from when he is a child until he comes to be an old man. And yet, if he's called the same, that's despite the fact that he's never made up from the same things, but is always being renewed, and losing what he had before, whether it's hair, or flesh, or bones, or blood, in fact the whole body.
PlatoA person who is good for anything ought not to calculate the chance of living or dying; he or she ought only to consider whether in doing anything he or she is doing right or wrong- acting the part of a good person or a bad person.
Plato