The ''sock and buskin'' are two ancient symbols of ''comedy and tragedy''. In Greek theatre, actors in tragic roles wore a boot called a "buskin". The actors with comedic roles only wore a thin soled shoe called a "sock". Some people refer to the masks of tragic and comedy as ''Sock and Buskin''.

A ''buskin'' is a knee- or calf-length boot made of leather or cloth whose laces closed, but is open across the toes. It was worn by Athenian tragic actors, hunters, and soldiers in Ancient Greek, Etruscan and Roman societies.

The word "buskin", only recorded in English since 1503 meaning ''half boot'', is of unknown origin. Figurative senses relating to tragedy are from the word being used (since 1517) to translate Greek "Kothornos" or Latin "cothurnus", the high, thick-soled boot; contrasted with "sock" (from Latin "Soccus"), the low shoes worn by Comedians.

More Info: en.wikipedia.org