The Serpent
The serpent in ancient times was symbolical of wisdom and subtlety, and, considered as a guardian spirit, is depicted on altars. It was also the symbol of Hygeia, the goddess of Health, from the tradition that Æsculapius assumed the form of a serpent during a pestilence in Rome.
In later art the serpent appears as a tempter. The Brazen Serpent of the Hebrews that gave newness of life to those who, bitten by the fiery dragon, raised their eyes to it, is an anticipation of the Crucifixion.