Castalia

Cyclopedia of Biblical, Theological and Ecclesiastical Literature

in Greek mythology, was a nymph, the daughter of the river-god Achelouns, who lived near Delphi, and from whom the Castalian spring has its name. She is said to have been very beautiful, and loved by Apollo, and to escape his attentions she threw herself into the spring. Thereupon the god selected this place as his favorite spot, ordered a temple to be built, and endowed the spring with animating virtues, so that whoever drank from it would become a poet. From this spring, as also from the spring Cassotis, the Pythian prophetess drank before she took the tripod.

The Nuttall Encyclopedia

A fountain at the foot of Parnassus sacred to the Muses; named after a nymph, who drowned herself in it to escape Apollo.