The Slang Dictionary: Etymological, Historical and Andecdotal

"All ridiculous words make their first entry into a language by familiar phrases; I dare not answer for these that they will not in time be looked upon as a part of our tongue."—SPECTATOR.
"Rabble-charming words, which carry so much wild fire wrapt up in them."—SOUTH.
"Slang derivations are generally indirect, turning upon metaphor and fanciful allusions, and other than direct etymological connexion. Such allusions and fancies are essentially temporary or local; they rapidly pass out of the public mind: the word remains, while the key to its origin is lost."
"Many of these [slang] words and phrases are but serving their apprenticeship, and will eventually become the active strength of our language."—H. T. BUCKLE.