Mercury, the Metal That Is Also the Planet

Mercury is unique among the seven metals in that its name is identical to its planet, and both take the name of the swift messenger god. Alchemically it is quicksilver, the one metal liquid at room temperature, running and uniting readily with other metals to form amalgams, behaviour that made it the very emblem of the volatile, the mobile and the transformative.

In alchemical theory mercury held a status beyond a single metal: the philosophical Mercury was one of the three principles, with Sulphur and Salt, the fluid, feminine, receptive principle present in all metals, and the alchemists distinguished sharply between common quicksilver and this philosophical Mercury. Its planetary pairing with Mercury the planet fits the god of messengers, merchants and boundaries, the swift and changeable. Mercury is genuinely toxic, a fact that shadows its long medical and alchemical use, from vermilion pigment to disastrous mercurial medicines. Its ritual and symbolic role is as the principle of flux and mediation, the go-between of the metallic world.