The Republic - pg. 87

"Doctors," I said, "would prove cleverest if, beginning in child-
hood, in addition to learning the art, they should be familiar
with very many and very bad bodies and should themselves
suffer all diseases and not be quite healthy by nature. For
I don't suppose they care for a body with a body - in that
case it wouldn't be possible for the bodies themselves ever
to be, or to have been, bad - but for a body with a soul; and
it's not possible for a soul to have been, and to be, bad and
to care for anything well."