The three philosophical principles of alchemy also known as The three primes, or the Tria Prima is a trinity made up by sulfur, mercury, and salt. Jabir ibn Hayyan first develops the sulfur, and Mercury understanding, and then it was expanded upon by Paracelsus who identified Sulfur, Mercury, and Salt as the three bodies in which Empedocles’s four classic elements existed.
Sulfur represents an expanding force, the essence, spirit, and transcendence. Sulfur is connected to the element of fire, and air. It is seen to be what gives motion, and is firing, and combustible, and represents the inner ambitions, and nature of the spirit that is within constructs, and entities. It is also connected to the masculine energetic aspects, and is associated with the sun, and the qualities hot, and dry. Sulfur is desire, ambition, and the fiery nature of the spirit.
Mercury is connected to the element of water, and Air, and is the balancing point between body, and spirit. It is the connection point that brings the spiritual, and the physical together, and allows them to communicate. Mercury is also greatly connected to the mind, intellect, knowledge, and wisdom. Mercury possesses the qualities of cold, and moist, and is connected to the feminine energetic aspects.
Salt is connected to earth, and water, and it represented the physical world. It would seem to be the exact opposite of sulfur, and is the more constricting force. Salt has the qualities of cold, and dry. Salt is the fixed principle, and is a balance, and Union between masculine, and feminine, and is sometimes seen to represent the child.