The choice of the verb "break" seems a strange choice for the phrase. Does anybody know where this phrase originated?
It appears that this may have some relation to an obsolete meaning of brake.
† brake, v.6
Etymology: perhaps repr. an unrecorded Old English *bracian , < bræc , which occurs in the sense of ‘phlegm, mucus, saliva’; compare Old Dutch braeken , Middle Low German and modern Dutch braken to vomit; allied to break n.1 (compare German sich brechen).
a. trans. and intr. To spue, vomit.
b. Cf. to break wind: see break v. Phrases 6.
I am involved in a Shakespeare production of Henry iv part one in which Falstaff complains that if he exerts himself any more he will break his wind ---- It seems an obvious fart joke (though of course the possibility remains that he is out of breath). I can't find any site allowing that this is the first use of the fart idiom though.
break wind was certainly widely used in the 17th century, but I'm still working on finding an earlier source. In other works of the 17th century, break wind appears to refer to either belching or farting, and often break wind upward is used to signify the former.
However, in A Briefe Discourse of a Disease Called the Suffocation of the Mother (aka hysteria) by Edward Jorden, printed in 1603, is a passage dealing with the fact that you cannot control certain bodily functions, such as your pulse. A glorious and fascinating passage deals with people who are attested to be able to control certain bodily functions though.
Galen ... bringeth an instance of a servant who killed himselfe to anger his master by holding of his breath. S.Augustine tells of one that could make himselfe to sweate when he list, by his imagnation only. Cornelius Gemma saith, that he knewe one that could weepe when he list: others that could make their bodies stiffe like an image, imitate the voyces of all kinde of creatures, raise a hickocke, and breake wind as often and in what maner they would. And S.Augustine tels of one that would make a kinde of musicke that way. Adrian Turnebus saw a rogue that gayned much money be shewing this feate, we do also see that some can counterfait madnes, some drunkennesse, some the falling sicknesse, some palsies and trembling, some can play the fooles and supply the roomes of innocents, some can make noyses and speake in their bellies or throates, as those which Hyppocrates calleth Eugastrimuthoi ventro loqui, such as was the holy maid of Kent, and Mildred of Westwall, &c.
In A Dictionary of the Anglo-Saxon Language by Joseph Bosworth (page 64) is a definition of the Anglo-Saxon verb Brecan, for which the given meanings are:
To BREAK, vanquish, overcome, weaken, open, move, excite, produce (italics are my own).
So, I think it's reasonable to say that breaking wind probably came from producing (or moving) wind.
I wish I could stop reading the Jorden book though, as I now want to know so much more about the holy maid of Kent, and Mildred of Westwall, and I love the witness of Adrain Turnebus (a French classical scholar, 1512-1565) that proves that "Le Pétomane" (Joseph Pujol) was nothing new.
I don't know for sure, but it's a very old phrase. From etymonline.com:
Break wind first attested 1550s.
Though we know that the expression is very old (16th century) we have no explanation. I assume the original saying was changed.
One might think of two sentences of forming winds in the intestines that break free and somehow the outcome some generations later was "to break wind". This is just a hypothesis as we have nowhere a hint as to the idea of this curious expression.
Of course, there may be other orginal formulations that were changed and shortened. In any case I can't imagine that the saying came into being as "to break wind".
In the Ardent Shakespeare copy of Henry IV, part 2 the editor has a note referencing a Thomas Cogan's "Heaven of Health" (1584). On apples, Cogan recommends to eat the seeds of Caraway apples along with the old apples "thereby to breake winde engendered by them." Sounds like a fart reference to me. I know someone mentioned Henry IV already, that's actually what brought me here!