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 YeatsWe all to some extent meet again and again the same people and certainly in some cases form a kind of family of two or three or more persons who come together life after life until all passionate relations are exhausted, the child of one life the husband, wife, brother, sister of the next. Sometimes, however, a single relationship will repeat itself, turning its revolving wheel again and again.
William Butler Yeats