Ouroboros, emblematic serpent of ancient Egypt and Greece represented with its tail in its mouth, continually devouring itself and being reborn from itself. A gnostic and alchemical symbol, Ouroboros expresses the unity of all things, material and spiritual, which never disappear but perpetually change form in an eternal cycle of destruction and re-creation.
In the 19th century a vision of Ouroboros gave the German chemist August Kekule von Stradonitz the idea of linked carbon atoms forming the benzene ring.