Full Idea
Ugliness is out of harmony with everything that is godly; beauty, however, is in harmony with the divine.
Clarification
'Beauty' is the Greek word 'kalos', which also translates as 'fine'
Gist of Idea
Beauty is harmony with what is divine, and ugliness is lack of such harmony
Source
Plato (The Symposium [c.384 BCE], 206d)
Book Reference
Plato: 'Complete Works', ed/tr. Cooper,John M. [Hackett 1997], p.489
A Reaction
This remark shows how the concept of 'harmony' is at the centre of Greek thought (and is a potential bridge of the is/ought gap).