Best source for origins of expressions and idioms? [closed]

I'm often interested in the origins of English phrases, and I know that I can find answers by googling, and I can find good answers by asking here.

How can I find good answers myself? Are there any well-known, respected, and fairly comprehensive sources for origins of English expressions and idioms?

Solution 1:

A handy source online is The Phrase Finder:

http://www.phrases.org.uk/

Solution 2:

I recommend Brewer's Dictionary of Phrase and Fable now at 16th edition.It is a bulky one -1326 pages

Solution 3:

Some other good online resources:

Online Etymology Dictionary (often has phrases within entries for individual words)
World Wide Words (Michael Quinion's archive of well-researched articles)
Wordwizard (excellent discussion-based site with a focus on word and phrase origins)

and ditto to @Robusto's answer. . .(usually)