A symbol is indeed the only possible expression of some invisible essence, a transparent lamp about a spiritual flame; while allegory is one of many possible representations of an embodied thing, or familiar principle, and belongs to fancy and not to imagination: the one is a revelation, the other an amusement.

What do we know but that we face one another in this place?

Time can but make it easier to be wise / Though now it seems impossible, and so / All that you need is patience.

Only the wasteful virtues earn the sun.

I agree about Shaw - he is haunted by the mystery he flouts. He is an atheist who trembles in the haunted corridor.

Words alone are certain good.

On limestone quarried near the spot By his command these words are cut: Cast a cold eye On life, on death. Horseman, pass by!