I want to be an American idiom

If there is a body of work that at first glance appears to be an entirely unnecessary edition to the library of a well-informed person, then it would be The Dictionary of Cliches.  The fact this book has had at least ten printings is rather ironic (no, really, check my post on irony).  The nature of the cliche is such that anyone fluent in the language already knows its meaning, making a dictionary redundant.  But before looking at the usefulness of this volume, here's a few definitions for clarity (with important differences italicized):

idiom— an expression that cannot be understood from the individual meanings of its elements and is peculiar  to a people or place

cliche— a trite stereotyped expression that has lost originality and impact thru overuse

proverb— a short popular saying usually of unknown ancient origin expressing a commonplace truth or useful thought

adage— a traditional saying expressing a common experience or observation, a proverb

saw— a sententious saying, maxim, proverb

maxim— an expression of a general truth or principle, particularly an aphoristic or sententious one

aphorism— a terse saying embodying a general truth or astute observation

slang— very informal usage in vocabulary and idiom that is characteristically more metaphorical, playful, elliptical, and ephemeral than ordinary language

A cliche can be an idiom, proverb, or adage as long as it is in common (over)use.  Time also appears to be a factor.  So much slang is so ephemeral that while it may be temporarily overused it also quickly falls out of common usage and becomes culturally antique.

But why a dictionary?  First off, to put collected knowledge into one place.  Students, teachers, writers, and English learners have easy access to the ideas and expressions prominent in our culture.  Expressions only vaguely understood are concretely defined.

More usefully, the origins/history and earliest usage of each cliche is included.  That's one advantage this dictionary has over Brewer's Dictionary of Phrase and Fable, a much more extensive volume of English idiom and allusion.  Many of the Brewer's entries list only definition (likely because an origin and history cannot be found or concisely stated). The following are few exerts from The Dictionary of Cliches.

More or Less— To a greater or lesser extent; maybe yes and maybe no; it's ambiguous.  How often one hears this formula for inexactitude and how old it is! It goes back to around 1225 in the Ancren Riwle, where it appears as "more oder lesse."

Now or Never— Here is one's last, or only, chance to do something.  The phrase dates at least from Chaucer's time (the 14th century), since he used it in Troilus and Criseyde (1380). The modern sense is clearer in John Daus's translation of Sleidanes Commentaries (1560): "Therefore thought they now, or els never, yt [that] God was on theyr side."

Proof of the Pudding is in the Eating— The way to test whether something came out as it was intended is to try it.  The pudding may look good on the table, but the only way to know for certain is to taste it. As you might expect, it is an old proverb.  One version of it dates to the 14th century.  A translation in 1682 of Boileau's Le Lutrin offered this: "The proof of th' pudding's seen i' th' eating."

Note the playful style and careful dating of each entry. Any saying older that last century is dated by usage in literature.  And most of the entries are old.  English idiom far predates modern spelling (In a some borrowed cases it predates English!).  I feel obligated to point out that the "proof" is NOT "in the pudding".

Knowing the origins of the phrases we use is important for any profession involving writing, creative or journalistic.  Or public (or publicized) speaking. Madelaine Murray O'Hare infamously used the phrase "the writing is on the wall." Had she realized its biblical origin, she probably would have refrained.

With the advent of instant information via the internet, there may be little demand for any sort of reference book, despite the credibility of information being substantially higher.  But my advice is to not judge this book by its cover. That's so cliche...