Diodorus says,(87) that there was a cavity upon Parnassus, from whence an exhalation rose, which made the goats dance and skip about, and intoxicated the brain. A shepherd having approached it, out of a desire to know the causes of so extraordinary an effect, was immediately seized with violent agitations of body, and pronounced words, which, without doubt, he did not understand himself; but which, however, foretold futurity. Others made the same experiment, and it was soon rumoured throughout the neighbouring countries. The cavity was no longer approached without reverence. The exhalation was concluded to have something divine in it. A priestess was appointed for the reception of its effects, and a tripod placed upon the vent, called by the Latins Cortina, perhaps from the skin(88) that covered it. From thence she gave her oracles. The city of Delphi rose insensibly round about this cave; and a temple was erected, which, at length, became very magnificent. The reputation of this oracle almost effaced, or at least very much exceeded, that of all others. At first a single Pythia sufficed to answer those who came to consult the oracle, as they did not yet amount to any great number: but in process of time, when it grew into universal repute, a second was appointed to mount the tripod alternately with the first, and a third chosen to succeed in case of death, or disease. There were other assistants besides these to attend the Pythia in the sanctuary, of whom the most considerable were called prophets;(89) it was their business to take care of the sacrifices, and to inspect them. To these the demands of the inquirers were delivered by word of mouth, or in writing; and they returned the answers, as we shall see in the sequel. We must not confound the Pythia with the Sibyl of Delphi. The ancients represent the latter as a woman that roved from country to country, venting her predictions. She was at the same time the Sibyl of Delphi, Erythræ, Babylon, Cumæ, and many other places, from her having resided in them all.