DR. ENGLISH: Neither 

Herodotus of Halicarnassus, the fifth-century BC Greek researcher and storyteller, is generally recognized as the world’s first historian. In his book The Histories, as translated by A.D. Godley in 1924, he supposedly wrote,

“It is said that as many days as there are in the whole journey, so many are the men and horses that stand along the road, each horse and man at the interval of a day’s journey; and these are stayed neither by snow nor rain nor heat nor darkness from accomplishing their appointed course with all speed.”

Sound familiar? Of course it does: That’s what some anonymous U.S. Post Office official decided was a pretty good description of mail carriers of the day, and so had inscribed on New York City’s James Farley Post Office, “Neither snow nor rain nor heat nor gloom of night stays these couriers from the swift completion of their appointed rounds,” a sentence often misrepresented as the U.S. Post Office motto. (From all appearances, the real motto is “Postage Due.”)

And it’s a good thing it’s not the real motto, because it comprises (just as Godley’s translation, we assume) a language error, given that neither, just like either, is restricted to a couple; i.e., not one or the other of two or, in either’s case, one or the other of two. The corrected version?

“Snow, rain, heat, or gloom of night doesn’t stay these couriers from the swift completion of their appointed rounds.” (This kind of harkens to “unalienable” vs. “inalienable” as used in the Declaration of Independence. Jefferson wrote “inalienable” and John Adams edited it to “unalienable,” which some people say is not a real word (like “reoccur”) and thus stands as proof that Harvard liberal-arts graduates like Adams are just a bunch of poorly educated liberal nitwits. As it so happens, however, either “inalienable” or “unalienable” is correct.)