This, naturally, gets the Writers and Polishers to wondering at the source(s) of some of these phrases. Being that information has never been easier to acquire than in the Internet age, we looked into a couple of the more common. We now share our findings with you:
The poor brass monkey
Since 1857, the brass monkey has been afflicted by cold, such as would freeze his tail off. This was the first such recorded use, in Before the Mast (by C.A. Abbey). Interestingly, exactly a decade prior, Herman Melville assigned a phrase to a character in Omoo asserting that "It was 'ot enough to melt the nose h'off a brass monkey." Variously, excessive heat or cold has been said to cost the poor brass monkey his ears, nose, whiskers, throat, tail or fur, as well as other, less appropriate bits of the monkey's anatomy, which first appear in the written record by the 1930s.
It should be noted that the brass monkeys in question are presumed, including by the generally recognized authority on word/phrase origins, the Oxford English Dictionary (OED), to be those small statues produced in China and Japan as tourist souvenirs beginning in the 19th century. There is an apocryphal attribution having to do with a stand on which canon balls are racked, but this story has a variety of problems which relegate it to the realm of quaint urban legend.
In the matter of using a witch's tit (or teat) as a yardstick for the cold, what's clear is what is not the colloquial source of the phrase. Contrary to popular belief that it is a vestige of witch-hunting centuries past, in which some stray bit of flesh could be used to convict a woman of consorting, and possibly engaging in unholy congress, with Old Scratch, the phrase first appears in the written record in <drumroll> 1932.
Yes, you read that correctly.
Again, the esteemed experts at the OED have been unable to turn up any use of the phrase prior to that year, when F. Van Wyck [pronounced "Wike"] Mason employed it in his novel, Spider House. While it is generally accepted that such terms are probably being used in conversation before someone writes them down, it nonetheless beggars belief that it could have existed for four or six or eight centuries without a surviving written reference prior to Mr. Mason. As such, it seems that it was coined by a person and with an intent now lost to memory, but in the relatively recent past, and probably as a straight-up metaphor.