Full Idea
What evidence could be brought if we were asked at this very moment whether we are asleep and are dreaming all our thoughts?
Gist of Idea
What evidence can be brought to show whether we are dreaming or not?
Source
Plato (Theaetetus [c.364 BCE], 158b)
Book Reference
Plato: 'Theaetetus', ed/tr. Waterfield,Robin [Penguin 1987], p.42