Full Idea
Could we attribute certainty to studying aspects of the world, such as how it arose, or acts, or is acted upon, when none of them ever was or will be constant? Of course not.
Gist of Idea
How can you be certain about aspects of the world if they aren't constant?
Source
Plato (Philebus [c.354 BCE], 59b)
Book Reference
Plato: 'Philebus', ed/tr. Waterfield,Robin [Penguin 1982], p.135