The winged disc
Thousands of years ago this was the symbol for Mercury:
The origins of this pattern are discussed here, however it remains one of the most popular designs in history. The caduceus became associated with commerce and negotiation, two realms in which balanced exchange were recognised as ideals. Speed was also cherished in automotive businesses which reflected the velocity of Mercury around the Sun. Today it still inspires corporate logos around the world:
The element associated with snakes is called mercury and its symbol (Hg) refers to hydrargyrum or “watersilver”. Since mercury isn’t really a solid it lacks a crystal structure and technically isn’t a mineral but rather a mineraloid. Embodying both the solid and liquid states, mercury was therefore the element of unity and with an atomic number of 80 it was often represented by a serpent. Mercury is the only metal for which the alchemical name became the common name.
Above: cinnabar or mercury sulphide (HgS)
In the crystalline structure above the snakes are apparent. The primary mercury ore is cinnabar, which when heated readily decomposes leaving behind pure, metallic mercury which sinks to the bottom of the vessel. The richest mercury ores contain up to 2.5 per cent mercury by mass.
Cinnabar generally occurs within volcanic veins and alkaline hot springs. The mineral resembles quartz in symmetry because it exhibits birefringence. To produce liquid mercury, crushed cinnabar ore is roasted in rotary furnaces. Pure mercury separates from sulfur in this process and easily evaporates. A condensing column is used to collect the liquid metal, which is most often shipped in iron flasks.
Once mercury is purified, it can dissolve metals such as gold and silver to form amalgams. Iron is an exception, and iron flasks have traditionally been used to trade mercury. Alchemists thought of mercury as the “First Matter” from which all metals were formed. In alchemy, this prima materia was the starting material otherwise known as The Philosopher’s Stone.
Mercury represents unity—the middle path between sound and light, time and space, liquid and solid. On a deeper level it is androgenous and like the sword in the stone represents the power of balance summed up by the word similitude. The Rod of Asclepius is therefore the implied middle way manifested by the balance of the fall equinox.
On a romantic level, the rearing snakes emerging from the disc (at top) represent twin flames—a soul that must split in two in order to return to physicality. This “twin soul” is a person who you feel connected to not just on a physical and emotional level, but also on the spiritual plane.
On another level the twin snakes represent sound and light in a special ratio that produces feelings of profound love in humans. The caduceus therefore, symbolises a ratio of different yet complementary wave signatures.
The heart shape above is formed from two fibonacci spirals that can also be drawn as twin snakes facing each other. The serpents of the caduceus represent duality and the eventual unification of polar opposites. As such, they speak of the balance required to strike harmony.