The Republic

Ten books of conversation that begin with an old man's remark about growing old and end with a myth of the dead choosing their next lives. In between: what justice is, whether it pays, what a city would have to look like to be just, and what kind of education could produce anyone fit to run one. The cave sits in Book VII, and it is offered as an image of education — not of metaphysics, and not of despair.

The book everything on the forebears' bench eventually cites. And the frame matters: the allegory is an argument about who should be made to govern, which is the last thing most retellings mention.