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.
William Butler YeatsCuchulain stirred, Stared on the horses of the sea, and heard The cars of battle and his own name cried; And fought with the invulnerable tide.
William Butler YeatsFor how can you compete Being honour bred, with one Who, were it proved he lies, Were neither shamed in his own Nor in his neighbour's eyes?
William Butler Yeats