Nose to the grindstone is an idiomatic expression, used to refer to the act of working continuously with no rest.
An expression that refers to a similar state of mind is In My Bag.
“Nose to the grindstone” refers to the work of a blacksmith, who had to spend several hours at a grindstone every day in order to sharpen weapons, as well as tools.
The expression comes from the anonymous English translation of Erasmus’ “Merry Dialogue”, published in 1557, although in this context, the phrase was used with a meaning that described a toilsome punishment.
It would be used in this manner during the rest of the 16th century, appearing in publications such as the 1585 “An Answere to a Certeine Booke” written by William Rainolds.
The phrase would need two centuries to pass, until it could be understood in its modern sense of performing hard work with complete focus.
Throughout the centuries, “Nose to the grindstone” appeared in a plethora of written sources, including newspaper publications, as well as drama and novels.
It started gaining a wider audience in the 19th century at which point it was already understood in its contemporary sense.
Although “Nose to the grindstone” is not the most popular idiom to exist in the English language, it is certainly widely used and recognized, even today.