Q From Scott Underwood: Recently I had a discussion about rack your brains and wrack your brains. The spelling seems to depend on whether one thinks the phrase derives from the rack, the medieval torture device, or from a variant of wreak or wreck, to destroy. I side with the former, though I realize I have no evidence. And it seems wrack and ruin has a similar confusion. I’ve been painfully stretching my brains over this question. Help!
A These expressions cause much confusion. Some style guides, such as Garner’s Modern American Usage, argue that the correct forms are rack one’s brains and wrack and ruin. The current edition of Fowler says equally positively that, at least in British English, rack is correct in both cases. Etymologists know that the forms of rack and wrack (and wreak and wreck) have become inextricably confused down the centuries and have identified so many historical examples of wrack one’s brains and rack and ruin that to insist on one over the other is etymologically insupportable. Dr Robert Burchfield, editor of the current edition of Fowler’s Modern English Usage, comments that “nine homonymous nouns and seven homonymous verbs” exist and despairingly adds “All the complexities of this exceedingly complicated word cannot be set down here; spare an hour (at least) to consult a large dictionary, especially the OED”. I can tell you from experience that doing so can leave you even more confused.
Let’s start by finding you the evidence that you lack for rack your brains, an idiom that has been known with wit and memory instead of brains. The earliest example known is in this poem:
Care for the world to do thy bodie right;
Racke not thy wit to winne by wicked waies.
Care For Thy Soule, by William Byrd, in his Medius of 1583, republished in Select poetry ... of the reign of Queen Elizabeth, by Edward Farr, 1845.
Rack, the verb, derives from the Middle English noun for a frame on which cloth was stretched for drying, so similar in sense to tenter. The modern noun rack retains this spelling. A century before William Byrd was writing, the noun had enlarged to mean the torture frame and more generally something that causes physical or mental suffering. The verb appeared about the same time, initially in senses that were associated with the stretching of cloth. By the middle of the next century it had extended to mean being racked with the pain of an illness, to twisting the meaning of words, and extorting money by outrageously increasing the amount demanded.
These historical sources might lead us to argue for rack one’s brain. However, by the seventeenth century, wrack was already being used; indeed, my non-scientific investigations suggest that it was more common than rack. Both are used today, with wrack more usual in the US and rack in Britain.
In your other expression, often spelled wrack and ruin, wrack is from a different source, Old English wrecan, to drive. In early usage, it meant vengeance or revenge; by the fifteenth century, it had taken on the idea of damage, disaster, or severe injury caused by violence. It is linked to wreak, as in to wreak havoc, and wreck, in the ship sense. (Wrack for seaweed is also a member of the set, as is the sense of high, fast-moving cloud, thought to be torn by the wind.)
The earliest example of wrack and ruin in the OED is dated 1659, but confusion between the spellings wrack and rack had already begun, because the form rack and ruin is known from a document of 1599 quoted in Thomas Fowler’s History of Corpus Christi College.
If you’re not totally confused by now, you surely should be. The best that I can do is to quote from another guide, which gives the standard US advice:
Probably the most sensible attitude would be to ignore the etymologies of rack and wrack (which, of course, is exactly what most people do) and regard them simply as spelling variants of one word. If you choose to toe the line drawn by the commentators, however, you will want to write nerve-racking, rack one’s brains, storm-wracked, and for good measure wrack and ruin. Then you will have nothing to worry about being criticized for — except, of course, for using too many clichés.
Merriam-Webster’s Dictionary of English Usage, 1994.