We have already spoken of the cauldron, but we remained entirely within its mythological aspect, as an archetypal symbol-very concrete, and too objective. Now, what does it mean as a psychological fact? For instance, when we dream of the mystic four of Pythagoras and the Greek philosophers, we naturally ask, what is the four anyway? That it obviously refers to the four functions is as near as we can get to it nowadays, but a thousand years from now people will be much farther along on the way. It may mean something that we cannot conceive of now. Originally it was the four sons of Horus, later the four Evangelists, and in the twentieth century the four functions. "That was their concretism," they will say. These old symbols are inexhaustible. They are not objects of the mind, but categories of the imagination which we can formulate in ten thousand different ways. They are inexhaustible because they are before the mind, the basis of everything mental. If you ask how I know, I have no absolute evidence. Another example is the Pueblo Indians' four cardinal points of the horizon, but they were already very civilized, we did not catch them at a sufficiently primitive stage to show the original unconscious form in which it existed.