Term

Quintessence

also known as the fifth essence, aether, ether

Definition

The fifth essence beyond earth, water, air, and fire — the subtle, incorruptible substance of the heavens. The alchemists identified it with the virgin first matter, here the goat Amaltheia and the agent of the Tabula Smaragdina, the ground from which the Great Work proceeds.

Etymology

Latin quinta essentia — 'fifth essence,' rendering Aristotle's aether.