Full Idea
Kant insists that the beautiful must not be tainted with the good (that is, not conceptualised in any way which would bring it into the sphere of moral judgement) yet he says that the beautiful symbolises the good, it is an analogy of the good.
Gist of Idea
The beautiful is not conceptualised as moral, but it symbolises or resembles goodness
Source
report of Immanuel Kant (Critique of Judgement I: Aesthetic [1790]) by Iris Murdoch - The Sublime and the Good p.209
Book Reference
Murdoch,Iris: 'Existentialists and Mystics', ed/tr. Conradi,Peter [Chatto and Windus 1997], p.209
A Reaction
Kant evidently wanted a very pure view of the aesthetic experience, drained of any overlapping feelings or beliefs. I'm not sure I understand how the beautiful can symbolise or be analogous to the good, while being devoid of it.