The Greeks undoubtedly believed in demons, but, different from the nations around them, considered the demons to be well-intentioned. Homer (c. 1000 B. C.) speaks frequently of demons, and in one instance in the Odyssey tells of a sick man pining away, "one upon whom a hateful demon had gazed." Empedocles (c. 490-430 B. C.) taught that demons "were of a mixed and inconstant nature, and are subjected to a purgatorial process which may finally end in their ascension to higher abodes." Yet he attributed to them nearly all the calamities, vexations, and plagues incident to mankind. Plato (427-347 B. C.) writes of demons good and bad, and Aristotle (384-322 B. C.), the son of a physician, speaks directly of "demons influencing and inspiring the possessed." Socrates (470-399 B. C.) claimed to have continually with him a demon--a guardian spirit. In Greece, in early days, physicians were looked upon as gods. Even after the siege of Troy, the sons of the gods and the heroes were alone supposed to understand the secrets of medicine and surgery. At a late period AEsculapius, the son of Apollo, was worshipped as a deity. When we speak of the art of healing in Greece, one naturally thinks of the apparent monopoly of the AEsclepiades, who ministered unto the Grecian sick for centuries. The original seat of the worship of AEsculapius was at Epidaurus, where there was a splendid temple, adorned with a gold and ivory statue of the god, who was represented sitting, one hand holding a staff, the other resting on the head of a serpent, the emblem of sagacity and longevity; a dog crouched at his feet. The temple was frequented by harmless serpents, in the form of which the god was supposed to manifest himself. According to Homer, his sons, Machaon and Podalirius, who were great warriors, treated wounds and external diseases only; and it is probable that their father practised in the same manner, as he is said to have invented the probe and the bandaging of wounds. His priests, the AEsclepiades, however, practised incantations, and cured diseases by leading their patients to believe that the god himself delivered his prescriptions in dreams and visions; for this imposture they were roughly satirized by Aristophanes in his play of "Plutus." It is probable that the preparations, consisting of abstinence, tranquillity, and bathing, requisite for obtaining the divine intercourse, and, above all, the confidence reposed in the AEsclepiades, were often productive of benefit.