Zohar Hadash, 38b-c.

Jewish Mysticism
“The likeness of the four beasts” (Ezek. 1-5). The likeness of what? The likeness of the supernal beasts, for from those that are visible those that are hidden and invisble are seen. Thus it is called likeness (demut) and it is called image (selem)… Here is a supernal secret- when the river comes forth from Eden all the souls that are the fruit of the Holy One, blessed be He, come out from it, and the one that takes them does so at the time that they come out before the Holy One, blessed be He. Each one enters into an image, to assume form in that place that is called likeness (demut), and they are the four beasts. Each one is formed there in the image that is appropriate to it. From there all these images are formed according to their form like one that enters a mould to be formed.

Translated by Elliot Wolfson in Through a Speculum that Shines- Vision and Imagination in Medieval Jewish Mysticism, Princeton- Princeton University Press, 1994.