Fountain
The fountain stands at the center and contains the water of life. The word comes from the Latin fons, meaning source. It is often located in the middle of a garden or square—essentially, in the center of a mandala. In the alchemists' rosarium (rose garden), there was always a fountain, a bath for renewal. The fountain is distinctly feminine, associated with Aphrodite, moisture, emotions, and eros—the “living water” that comes from the underworld.
Because the fountain is “the treasure that is hard to find,” the location where it stands is secret. Only with “great effort and God's grace did the philosophers find the noble fountain” ("Gloria Mundi", cited in CW14, par. 341), and so forth.
The water of the fountain is shot up and falls down to be shot up again, creating a circulation, an image of opus circulatorum, the circulating work, rising and descending. The act of being shot up to spread out can also be compared to a tree, whose trunk rises and ends with a crown that spreads out. (This image was developed by alchemists to depict the leaves falling, burning, after which the heat was absorbed by the tree, giving rise to new leaves that fell, burned, etc.) It can be seen as an allegory for expanded consciousness.
This continuous flow, this ascending and descending, circulating process between the unconscious and the conscious, made up of the water of life and leading to transformation, makes the fountain intimately associated with Mercury.