The origin of words is often " a red herring" as it is possibly misleading, or based on non historical sources, etc.
Having said that, nothing works better for an understanding of the etymology that the annex at the mathematician and philosopher, Samuel Reiss, who in a quite unknown book expressed the uphill strugle to find the origen of meaning, beyond the corpse of words themselves. Samuel Reiss: The universe of meaning.
New York, Philosophical Library, 1953. 227 pp. ( P F Strawson's review.)
Some of his works, here.
Today, a couple of books:
Patrick Carroll reviews Dirty Words:Even if the conclusions that Jack comes to are not the end all be all, they certainly do entertain and give food for thought. In many ways, the book is like a cultural history of England as well. I learned about as much about the idioms as I did about the lives of everyday people throughout the history of the British Isles.
Red Herrings and White Elephants
What flower takes its name from the human testicle? Is your husband rantallion? Does your wife sport a merkin? What's a wittol, and why were they once drummed out of town while sitting backwards on a horse? Is sacofricosis a crime, a disease or an hors d'oeuvre? Morton roams through centuries of etymological lore to explain the origins of the language of love and sex. It is the perfect book for language-lovers and lovers alike.
Albert Jack reports:
Tracing the phrases to their origins is hard work but Jack's effort revealed that most of them originated from interesting, if not unexpected, sources. Not all of the provided sources and origins are clear since most of them have evolved over the years, with their roots lost in time. In cases which the root is ambiguous, the author is nice enough to mention that, bringing up the most plausible, and in some cases the funniest, origin which he thought most likely.
It is interesting to note that most of the sayings do not even originate from the English language, and are cobbled up from Anglo-Saxon, Latin, Greek, French, Swedish, Norse (when it's raining cats and dogs or when someone went berserk), Hindustani (when someone has gone Doolally), Jewish (when you tell someone to eat his heart out) and even Gaelic (when you declared something as phoney), just to name a few.
The sources are as varied as well, with some coming from famous stories such Aesop's fables, Greek and Roman legends, and even from the Bible.