(Greek), Parnassus (Latin). A mountain near Delphi, in Greece. It has two summits, one of which was consecrated to Apollo and the Muses, the other to Bacchus. It was anciently called Larnassos, from larnax, an ark, because Deucalion's ark stranded there after the flood. After the oracle of Delphi was built at its foot it received the name of Parnassos, which Peucerus says is a corruption of Har Nahas (hill of divination). The Turks call it Liakura.
“Where lies your vein? Are you inclined to soar to the higher regions of Parnassus or to flutter round the base of the hill?” (The Antiquary)- i.e. Are you going to attempt the higher walks of poetry, such as epic and dramatic, or some more modest kind, as simple song?
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894