There’s an advertisement I’ve been hearing on the radio in the mornings: it’s for a local business, and it’s voiced over by the business owner himself, common for local ads. He tells you that his business is a good one, but says that “the proof is in the pudding,” and you should come in and see for yourself.
I’ve heard that phrase quite often, recently, for some reason. Only, it’s the wrong idiom. The proof is not in the pudding.
The proof of the pudding is in the eating.
The wrong version doesn’t even make any sense, though, of course, few people actually try thinking about the standard phrases they use. That’s why one hears things like, “It’s his stock and trade,” which should be “stock in trade.” It’s why one sees people expressing support for someone’s position by writing, “Here, here!” (It should be “Hear, hear!”, as in “Listen to this guy!”) And it’s why one comes by the most nonsensical one of all, “I could care less,” rather than “I couldn’t care less.”
“Proof”, here, doesn’t refer to the more common meaning today, of “evidence”, but to an older meaning, a test of quality. We seldom use the word in that sense now as a noun (it does survive, at least for a little longer, as a photographic proof sheet (test sheet), and as printer’s proofs), but we still see it as a verb when we proof the yeast for bread-making, and when we proofread text — those of us who don’t rely overmuch on the spelling checker.
The sentence as a whole is one of the many that come to us through the truly marvellous book Don Quixote, but there are earlier references to similar adages, and Cervantes undoubtedly was using an already established saw, which, then, of course, was translated.
I’ve written before about what a great book Don Quixote is. But don’t take my word for it: read it; the proof of the pudding is, after all, in the eating.