Full Idea
What is perfectly good can accomplish only what is perfectly beautiful; this was and is a universal law.
Gist of Idea
Perfect goodness always produces perfect beauty
Source
Plato (Timaeus [c.362 BCE], 30a)
A Reaction
Beautiful must be 'kalon', which is better understood here as fine and noble, rather than looking pretty. This is a quintessential Plato opinion. At the highest level, the supreme Forms endorse one another. He is discussing cosmic creation.
Book Reference
Plato: 'Timaeus and Critias', ed/tr. Waterfield,Robin [OUP 2008], p.18
Related Idea
Idea 391 We could express the Good as beauty, proportion and truth combined [Plato]