On a helical staircase

I like this passage on purism in language use, from Follett’s Modern American Usage (1966):

Purism is another form of the pedantic. It singles out in the language of science and scholarship what is literal and minute, as pedantry does the abstract and long-winded. Purism haggles over trifles and refuses to know when errors and confusions no longer matter. We all understand what a spiral staircase is; the purist reminds us that a spiral lies flat in one plane, so that our staircase is properly a helix. But even if each of us has his own one or two pet pedantries, collectively we shall not go down the helical staircase. We shall continue to drink a cup of coffee aand assuredly not a cupful; we shall speak of captions below the text, though caption by a confused etymology suggests head; we shall refer to the proverbial man of straw, though he is not the subject of a proverb; we shall speak of being buttonholed by a bore and not buttonheld, from the supposedly correct buttonhold; we shall say it is no use when we speak, though we may want to write it is of no use; we shall certainly cross the bridge (but not till we come to it), instead of agonizing over the truth that it is the river that is crossed and not the bridge. And if the world, faced with a new and inspiriting phenomenon, wants to say outer space, we shall not affect to be puzzled on the plea that space cannot be inner or outer. If there is an outer darkness there can be an outer space, which we may even hope to visit.

Wilson Follett died with this book unfinished. Jacques Barzun and several other hands took up the work of revising and editing.