The assumption of the form of a serpent by the god of medicine was not an extraordinary thing, according to ancient beliefs. Plenty of instances might be cited. I may give one. Alexander the Great was believed by many to have been not the son of Philip, but of Jupiter Ammon, who appeared to Olympias in reptilian shape. Plutarch tells the story. It is amusingly related of Philip that “he lost one of his eyes as he applied it to the chink of the door, when he saw the god, in the form of a serpent, in his wife’s embraces.”[37] The ability to take on at pleasure any animal or other form was regarded as one of the distinguishing prerogatives of divinity. Taking it for granted, then, that there was really a serpent transferred from Epidaurus to Rome, which was regarded as Æsculapius, the interesting question arises, of what species was it? A very conclusive answer may be given. It is known that at the Epidaurian Asclepion a species of serpent existed in considerable numbers by permission. After stating that all serpents, “but particularly those of a more yellow color, are considered as sacred to Æsculapius, and are gentle and harmless toward men,” Pausanias says: “They are alone nourished in the land of the Epidaurians; and I find that the same circumstance takes place in other regions.”[38] Here, then, is proof that there was a species of serpent which deserved to be characterized as Æsculapian. [Illustration: FIG. 2.—THE ÆSCULAPIAN SERPENT.] It being reasonably certain that only one kind of serpent “was nourished in the land of the Epidaurians,” and regarded as sacred to Æsculapius, the following passage from Pliny is interesting: “The Æsculapian snake was first brought to Rome from Epidaurus, but at the present day it is very commonly reared, in our houses even; so much so, indeed, that, if the breed were not kept down by the frequent conflagrations, it would be impossible to make head against the rapid increase of them.”[39] It is evident from this statement that the serpent in question was not venomous, that its presence was prized, and that people would not wilfully kill it.