Our soul serves as the essential bridge between these two worlds. Like Being, it is (Socrates says) immortal and rational. But it also dwells in the world of Becoming, because of its adherence to the body. On one side of the bridge lies a world of error and illusion; on the other, of wisdom and truth. Yet for most people—indeed, for all but a very few people—that bridge has been washed out. Here the metaphor Plato preferred was not that of a bridge but that of a cave. It appears for the first time in Book VII of his most famous dialogue, the Republic,
