What is the literal origin of this "fine point" (if any?). Here's a chunk of the Boston Globe column I wrote in 2009 asking that question. (I omit the paragraph in which I inaccurately called Henry James a fan of "not to put too fine a point on it." Well, he should have been!)
It's tempting to read the phrase as a pen-based metaphor, an explanation offered at the British etymology site The Phrase Finder: "I would imagine it has its origins in either pencils or quill pens which would be used for delicate work if sharpened to a fine point, but for cruder stuff if left blunt.'' But no other source seconds that appealing theory.
I thought the answer was about to emerge last month, when Patricia O'Conner wrote about the phrase at her Grammarphobia blog. But no: She is as baffled as everyone else. "The OED describes the usage as figurative,'' she reports, "but doesn't say exactly what the figure is. Go figure.''
As she says, the Oxford English Dictionary doesn't give the answer, but it does offer clues: In the entry for fine, the cross-reference for "put too fine a point'' (listed under point) appears under the sense of fine applied to tools and weapons: "sharp-pointed, keen-edged.'' The figurative examples come from Shakespeare ("blunting the fine point of seldom pleasure,'' 1600) and Bacon ("the finer edges or points of wit,'' 1622). These uses blend the idea of a sharp tool with a refined apprehension, and other early uses of "fine point'' share that notion.
These examples are often positive, not negative; today, we're always not putting too fine a point on it, but that wasn't always the case. For instance, in an 1842 issue of The Knickerbocker, a New York literary monthly, a writer sardonically advised readers, "If any passage appears to you as dull, consider it a piece of latent wit, whose point is too fine for your obtuse perceptions.''
And the Warren Street Chapel, according to an 1861 "Historical Sketch of Boston,'' was not only a refuge for the destitute: "It aims also to benefit those who, 'to put a fine point upon it,' are in less favored circumstances as regards the means of a true culture.''
If a fine point is a delicate bit of wit or observation, "too fine a point'' implies language that is too refined for the immediate purpose, more polite than the object deserves. This sense seems to emerge seamlessly from earlier figurative uses of fine and point, without reference to anything so concrete as a quill and penknife. If it's more opaque now than it was to earlier writers, that may be because we're far less concerned with gradations of subtlety.