One of the earliest Greek gods to specialize in healing was Asclepius (known to the Romans as Aesculapius). Healers and those in need of healing invoked Asclepius' name in prayer and healing ceremonies in temples and at home. A healing clan known as the Asclepiads claimed to be the descendants of Asclepius and to have inherited a knowledge and mystical power of healing from him.
Asclepius did not begin as a god, however. It is now thought that he was an actual historical figure, renowned for his healing abilities. When he and his sons, Machaon and Podalirios, are mentioned in The Iliad in approximately the 8th century B.C.E., they are not gods. As his "clan" of followers grew, he was elevated to divine status, and temples were built to him throughout the Mediterranean world well into late antiquity.
Images of Asclepius are generally recognizable by his beard and staff with a single snake. In this image, he is accompanied by his small, mysterious attendant, Telesphoros.
Temples to Asclepius were erected throughout the ancient Mediterranean. Those seeking healing would make pilgrimages to the sites and might perform prayers and sacrifices, make monetary gifts, or spend the night in the temple.
Many modern physicians have adopted the caduceus as the "ancient" symbol of their profession, with its two intertwined snakes grasping a staff. In the ancient world, however, the caduceus was a symbol of Hermes, the Roman Mercury, who was primarily a messenger god linked with commerce. Asclepius' symbol was a single snake entwined around his staff- the 'Asclepian staff'.
The snake symbolized rejuvenation and healing to many ancient Mediterranean cultures. On this 17th-century title page, the single-snake staff of Asclepius and the double snake of the caduceus appear with other ancient medical images involving snakes.
Taken from: Marco Aurelio Severino. Viper Pythia. (Patavii: Typis Pauli Frambotti, 1651).