Brewer's: Thespis, Thespian
Dramatic. Thespis was the father of Greek tragedy.
The race of learned men, ... oft they snatch the pen, As if inspired, and in a Thespian rage; Then write.
Thespis, the first professor of our art, At country wakes sang ballads from a cart.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894