C.G. Jung Letters, Vol. 1: 1906-1950
A further stage of the projection already reaches a sort of conclusion.
That is, one begins to suspect that the effective thing is something definite, not just the celestial vault, the wide earth or the vast sea.
The existence of definite substances is suspected, and then one has already come nearer to a definition of the prima materia.
For instance, let us imagine the prima materia is water, water is a mysteriously determined power which can also evaporate as steam.
By this analogy we have come nearer to understanding the prima materia: it is similar to water, subject to mysterious laws which impress us in a marvellous way.
Think, for instance, of the definition of the Tao in Lao-Tse’s “Tao-te Ching”, where he says that the Tao is like the nature of water, it always seeks the deepest place.
The secret power of water lies in its infallible faculty of knowing the deepest place and finding it.
It was this which impressed our forefathers so deeply; and when they speak of “water” it is the essence of the unconscious that they describe.
This essence is a peculiar wisdom of nature, a knowledge which man does not possess, an instinctive knowledge, a conformity to obscure laws, totally inexplicable to naive man.
The mysterious operative in nature, which determines us, is therefore said to be of the nature of water.
But it is not tangible like water itself; we read in the Rosarium, for instance, that it is “aqua sicca” (dry water), it does not moisten the hands. ~Carl Jung, ETH Lecture XI, 11July1941.