back to The Seven Metals
The texts reads: "Visit the interior of the earth, and rectifying, you will find the hidden stone".
Mercury is central, as it is the symbol for the matter to be worked on.
Moon and Sun are not only symbols for the second (whiteness) and third stage (Redness) of the Great Work, but they are also used for the duality present in the Work: the Volatile and the Fixed, two principle that go hand in hand in the process of continued distillation. The moon or the Volatile is the passive principle of the mind, and the Sun or the Fixed is the active principle of the mind.