Idiom of the Week—“Keep Your Nose to the Grindstone”

To “keep your nose to the grindstone” means to apply yourself conscientiously to your work.  There are two rival explanations as to the origin of this phrase. One is that it comes from the supposed habit of millers who checked that the stones used for grinding cereal weren't overheating by putting their nose to the stone in order to smell any burning. The other is that it comes from the practice of knife grinders when sharpening blades to bend over the stone, or even to lie flat on their fronts, with their faces near the grindstone in order to hold the blades against the stone.  All the evidence is against the miller's tale, most because the stones used by millers were commonly called millstones, not grindstones. The two terms were sometimes interchanged but the distinction between the two was made at least as early as 1400. 

The first known use of this phrase in print occurred in 1532 in an obscure work by John Frith:

"This Text holdeth their noses so hard to the grindstone, that it clean disfigureth their faces."

The phrase appears in print at various dates since the 16th century. It was well-enough known in rural USA in the early 20th century for this picture, taken from around 1910, which alludes to the 'holding someone's nose to the grindstone' version of the phrase, to have been staged as a joke.