Alchemical Sulfur, Mercury and Salt

Western occultism (and, indeed, pre-modern Western science) is strongly focused on a system of four of five elements: fire, air, water, and earth, plus spirit or ether. However, alchemists often spoke of three more elements: mercury, sulfur and salt, with some focusing on mercury and sulfur.

Origins

The first mention of mercury and sulfur as base alchemical elements come from an Arab writer named Jabir, often Westernized to Geber, who wrote in the late 8th century.

The idea was then transmitted to European alchemist scholars. Arabs already used the system of four elements, about which Jabir also writes.

Sulfur

The pairing of sulfur and mercury strongly corresponds to the male-female dichotomy already present in Western thought. Sulfur is the active male principle, possessing the ability to create change. It bears the qualities of hot and dry, the same as the element of fire; it's associated with the sun, as the male principle always is in traditional Western thought.

Mercury

Mercury is the passive female principle. While sulfur causes change, it needs something to actually shape and change in order to accomplish anything. The relationship is also commonly compared to the planting of a seed: the plant springs from the seed, but only if there is earth to nourish it. The earth equates to the passive female principle.

Mercury is also known as quicksilver because it is one of the very few metals to be liquid at room temperature.

Thus, it can easily be shaped by outside forces. It is silver in color, and silver is associated with womanhood and the moon, while gold is associated with the sun and man.

Mercury possesses the qualities of cold and moist, the same qualities ascribed to the element of water. These traits are opposite those of sulfur.

Sulfur and Mercury Together

In alchemical illustrations, the red king and the white queen also sometimes represent sulfur and mercury.

Sulfur and mercury are described as originating from the same original substance; one might even be described as the opposite gender of the other--for example, sulfur is the male aspect of mercury. Since Christian alchemy is based on the concept that the human soul was split during the fall season, it makes sense that these two forces are seen as initially united and in need of unity again.

Salt

Salt is an element of substance and physicality. It starts out as coarse and impure. Through alchemical processes, salt is broken down by dissolving; it's purified and eventually reformed into pure salt, the result of the interactions between mercury and sulfur.

Thus, the purpose of alchemy is to strip down the self to nothingness, leaving everything bare to be scrutinized. By gaining self-knowledge about one's nature and one's relation to God, the soul is reformed, the impurities expunged, and it is united into a  pure and undivided thing. That is the purpose of alchemy.

Body, Spirit and Soul

Salt, mercury and sulfur equate to the concepts of body, spirit and soul.

Body is the physical self. Soul is the immortal, spiritual part of the person that defines an individual and makes him unique among other people. In Christianity, the soul is the part that is judged after death and lives on in either heaven or hell, long after the body has perished.

The concept of spirit is far less familiar to most. Many people use the words soul and spirit interchangeably. Some use the word spirit as a synonym for ghost. Neither is applicable in this context. The soul is personal essence. The spirit is a sort of medium of transference and connection, whether that connection exists between body and soul, between soul and God, or between soul and the world.