Full Idea
Someone who believes in the beautiful itself, can see both it and the things that partipate in it, and doesn't believe that the participants are it or that it itself is the participants.
Gist of Idea
Believers in the beautiful see that it is separate from things that participate in it
Source
Plato (The Republic [c.371 BCE], 476c)
Book Reference
Plato: 'Complete Works', ed/tr. Cooper,John M. [Hackett 1997], p.1103
A Reaction
Note that you required to 'believe in' the beautiful. It is hard to see much connection between a beautiful football goal, a beautiful bird and a beautiful maths proof. Someone suggested that Greek 'kalon' just means 'wow!'.