Tragedy. The Greek tragic actors used to wear a sandal some two or three inches thick, to elevate their stature. To this sole was attached a very elegant buskin, and the whole was called cothurnus. (See Sock .)
Or what (though rare) of later age Ennobled hath the buskined stage.
Milton: Il Penseroso, 79, 80.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894