Why does “Whip smart” come to mean “Very smart”?
Solution 1:
There is a smart play on words in the idiom as smart as a whip. In this particular idiom, either meaning seems to make sense.
Smart: adjective
informal Having or showing a quick-witted intelligence.
As in: if he was that smart he would never have been tricked
Smart: verb
(Of part of the body) feel a sharp stinging pain.
As in: her legs were scratched and smarting.
(as adjective smarting) Susan rubbed her smarting eyes.
And whip is defined this way by Online Etymology Dictionary-
Whip
"instrument for flagellating," early 14c., from whip (v.) and perhaps in part from Middle Low German wippe "quick movement."
An article that I looked up on the Internet states this-
Smart as a whip, but far from as pliable, he comprehended more in a moment than the balance of the quartet could grasp in a week.
But the practice is an old one. Doctor Tempete is mentioned by Rabelais as a celebrated flaggelator of school-boys, in the college of Montaigne, in Paris. Buchanan was wont to tickle his royal disciple, James the First, and joked with the ladies of the court about it. And, with respect to that of our public schools, it may be of service; for every one must allow it makes a boy smart.The fact of the matter is that as early as the 17th century the word smart meant both to be strong, quick, and intense in manner and to be painful. So while a whip might cause pain and smart, someone would be strong, quick, and intense in manner in the same way a whip is strong, quick, and intense.
Source: Article 1
In another article, the possibility of a pun was mentioned.
I had not noticed whipsmart before and hardly know what it is supposed to mean. I take it that most people who use it mean ‘clever’ by smart. That goes with the American origins of the term.
But the word smart had for centuries borne the primary meaning of ‘stinging’, as with a rod or whip. In Psalm 32, the Sternhold and Hopkins metrical version has: ‘Both night and day thy hand on me / So grievous was and smart.’ In the meantime, a specialised meaning ‘lively’ had developed, and by the 19th century anyone under orders could expect to be told ‘Look smart!’ as an alternative to ‘Look lively!’
Source: Article 2
I also found a third explanation.
It is actually "quick as a whip" because whips are usually quite fast. The saying is used to mean that someone is smart though.
Source: Yahoo answers
The author seems to support only one meaning of the word smart here-
The origin of the phrase refers to “smart” not as a level of intelligence, but is instead an indicator of pain, as in “It really smarts when you stub your toe”.
In the days of horse-drawn vehicles one was often able to urge on the horse merely by flicking or cracking a whip near the animal, and if that failed, you could be sure of results by seeing that the flick or crack touched him lightly. The expression must have arisen from that widespread exercise.
An expression in use early in the 19th century was ‘smart as a steel trap,’ which does indeed operate smartly too, but by 1860 the ‘Mountaineer’ in Salt Lake City was printing: ‘Mr. A___ was a prompt and successful businessman, ‘smart as a whip,’ as the Yankees say.”
Source: Article 3
In my opinion, the idiom, a simile, can either refer to the quickness of the action of cracking a whip, the stings or the smarts caused by the cracking of a whip or the result of flaggelating little school boys through their schooling years to bring out the brighter side of their minds.
Solution 2:
As described by @Hot Licks in the comments:
smart as a whip
Informal, chiefly North American Very quick-witted and intelligent: despite some of the things he says, he’s smart as a whip
Where speed equates to intelligence, the whip analogy works. The end loop actually breaks the sound barrier, so it's very fast indeed. http://www.scientificamerican.com/article/true-cause-of-whips-crack/
Edit: Digging a little more, I found this as an origin:
"What's so smart about a whip? Delving into the history of smart, we find that the word first meant "inflicting or causing pain" (1023). Gradually the adjective took on additional meanings, including "having a certain degree of integrity, force, and strength (1184) as in "look smart!" and, by extension, "clever in thought or argument" (1639). Smart as a whip punderfully unites the original signification and the most pervasive (at least in the U.S.) meaning of smart. " http://digitalcommons.butler.edu/cgi/viewcontent.cgi?article=2062&context=wordways
It cites no sources, but is at least as plausible.
Solution 3:
Smart as a whip:
according to The Phrase a Finder the expression originates from the use of a whip during the horse-driven vehicle period:.
- "Bright, clever, alert. A whip 'smarts' and operates with snap. In the days of horse-drawn vehicles one was often able to urge on the horse merely by flicking or cracking a whip near the animal,' and if that failed, you could be sure of results by seeing that the flick or crack touched him lightly. The transfer must have arisen from that widespread exercise' An expression in use early in the 19th century was 'smart as a steel trap,' which does indeed operate smartly too, but by 1860 the 'Mountaineer' in Salt Lake City was printing: 'Mr. A___ was a prompt and successful businessman, 'smart as a whip,' as the Yankees say."
- From "Dictionary of Cliches" by James Rogers (Wings Books, Originally New York: Facts on File Publications, 1985).
- Whip smart as a fixed expression appeared in the mid 1980's
Ngram: smart as a whip vs whip smart.
Solution 4:
From Online Etymology, smart in Old English (Proto-Germanic smarta-) meant "be painful". In late Old English, smeart meant painful, severe, stinging; causing a sharp pain. Only in the 1300's did it come to be used as ""quick, active, clever".
Smart as a whip almost certainly came from British "whip-smart" and initially tied it to the pain of the tip of a whip.
This 1815 passage was the first I could find of the two words in succession:
Though it was undoubtedly more common as Dickens used it:
The wheels skim over the hard and frosty ground; and the horses, bursting into a canter at a smart crack of the whip, step along the road as if the load behind them...
I can't find a better connection (I don't subscribe to the OED) but a jump from smart/painful used with whip to intelligence isn't a big leap. The same thing happened with sharp.
Solution 5:
The earliest match I could find for the exact expression "smart as a whip" is from "The Right Man in the Right Place" in the [Cincinnati, Ohio] Penny Press (February 6, 1860):
John ——— was boarding at the National Hotel, at which a Mr. ———, a Connecticut manufacturer, also stopped when doing business in town. Mr. A——— was a prompt and successful business man, "smart as a whip," as the Yankees say, and withal (when business was "all "done up snug") a genial, social companion, which naturally enough accounted for his sometimes perambulating with something heavy in his hat!
This instance is especially interesting because the author refers to it as something "the Yankees [that is Northerners] say." I couldn't find any prior instances from farther North, but the St. Cloud [Minnesota] Democrat (November 5, 1863) has this item, under the heading "A Rich Story":
Do any of you know old Bill Lowery? He moved from Springfield to some point in Minnesota. Bill is tough, smart as a whip, keen as a briar, but then, like all of us fellars, Bill loves to see the bottom of the tumbler at all times!
Christine Ammer, The Facts on File Dictionary of Clichés, second edition (2006) has this entry for the phrase:
smart as a whip Very clever, highly intelligent. The sharp crack of a whip has been a metaphor for mental quickness since the mid-nineteenth century in America. "He was as smart as a whip," wrote B. F. Taylor (World on Wheels, 1874), one of the early appearances of this expression in print. Several writers, among them Harriet Beecher Stowe and Erle Stanley Gardner, have used smart as a steel trap, presumably alluding to its rapidly closing on some hapless creature, but it has not replaced the older simile.