Full Idea
There is not a single sound reason for positing the existence of such a being who is immortal
Gist of Idea
There isn't a single reason for positing the existence of immortal beings
Source
Plato (Phaedrus [c.368 BCE], 246d)
Book Reference
Plato: 'Phaedrus and Letters VII and VIII', ed/tr. Hamilton,Walter [Penguin 1973], p.51