I owe this word, like richard, to Robert van Gulik’s Chinese detective novel The Willow Pattern.  In the book, murder has been done and a search for clues is underway:

     Judge Dee began with the floor of the portico.  Suddenly he stooped.  A crumpled piece of white cloth was lying against the socle of the third pillar.  Squatting down, he called out: “Bring the candle, Tao Gan!”

Unlike “richard,” “socle” is a real word, a standard if rarely used architectural term, and thus testimony to van Gulik’s exactitude in technical description.  It means a “low plain block or plinth serving as a pedestal to a statue, column, vase, etc.”  So the OED, which follows the history of the word back through the diminutive form socculus to the Latin soccus, “a light low-heeled shoe or slipper.”  Soccus is also the ancestor of our word “sock.”  A pleasing fantastic image: architectural columns wearing socks, perhaps fallen down in loose rolls about the column feet, as used to be the case with socks, or my socks anyway, before the advent of elastic fabrics.

“Sock” has had many developments, ranging from “bobby-soxer” and “Red Sox” onward to the slang phrases “knock the socks off” and “put a sock in it,” though not to “sock” in the sense “hit on the jaw,” which apparently has a different source (“of obscure origin,” says the OED).  The most interesting figurative meaning of “sock” is theatrical.  Conventional wisdom has it that while tragic actors in ancient Greece and Rome wore “buskins,” substantial boots with heels high enough to produce a suitable elevation onstage, those low-down fellows the comic actors wore “socks,” light-soled, sandal-like shoes.  Hence “buskin and sock” as a metonym for “tragedy and comedy.”  Thalia, the muse of comedy, may be viewed in fetchingly sandaled guise in a painting by the seventeenth-century artist Giovanni Baglione,

or more irreverently, more truly comically perhaps, in a cartoon by Seamus Patrick Burke:

Source: www.spburke.com

It’s the Thaliaesque, comedy-tonight meaning of “sock” which you’ll need if like Judge Dee you are searching for a clue, not to a murder but to the meaning of a tribute to the comic dramatist Ben Jonson which John Milton put into his poem “L’Allegro”:

Then to the well-trod stage anon,
If Jonsons learned Sock be on . . .