In ancient and medieval times, the concept of mercury encompassed both the planet Mercury and the metal mercury (also known as quicksilver). Early alchemists believed in a correspondence between the macrocosm (the universe) and the microcosm (the earth and human beings), a principle often referred to as the "Doctrine of Signatures" or "As above, so below."

- Mercury (planet), the closest planet to the Sun

- Mercury (element), a chemical element

- Mercury (mythology), a Roman deity

synthesis of gold in modern science (physical alchemy):

neuron bombardment of mercury (element)