Coleridge on Allegory and Symbol

Now an Allegory is but a translation of abstract notions into a picture-language which is itself nothing but an abstraction from objects of the senses; the principal being even more worthless than its phantom proxy, both alike unsubstantial and the former shameless to boot.  On the other hand, a Symbol is characterized by a translucence of the Special in the Individual or of the General in the Especial or of the Universal in the General.  Above all by the translucence of the Eternal through and in the Temporal.   It always partakes of the Reality which it renders intelligible; and while it enunciates the whole, abides itself as a living part in that Unity, of which it is the representative.  The other are but empty echoes which the fancy arbitrarily associates with apparitions of matter.

--Samuel Taylor Coleridge from The Statesman's Manual