If you want to express that a given thing's quality can only be ascertained through firsthand experience, or if you're referring to a truth that's thoroughly supported by evidence, you might say, "the proof is in the pudding." It is one of those sayings that has become so established that you don't give much thought to how weird it actually sounds. When the heck did pudding come into the equation? Why pudding, specifically? Were those little chocolate pudding cups really something that needed to be thoroughly investigated for authenticity? Well, if it makes you feel any better, the full version of the saying makes a lot more sense — as does the fact that it's not referring to pudding as you are likely thinking of it.
The full version of the quote is: "The proof of the pudding is in the eating." This means just what it sounds like: The only way to determine the quality of a pudding is by tasting it. The phrase was coined back in the 17th century, when the word "proof" referred primarily to a test of quality (as in "proving one's worth") rather than the modern usage, meaning "evidence.
" The pudding the saying refers to is savory pudding, not sweet So where does pudding come into this? Well, the "pudding" of the saying doesn't refer to chocolate pudding cups, nor , nor . It doesn't even refer to dessert in general, as is often the case in the United Kingdom. It refers instead to savory pudding, which consists of minced meat wrapped in some kind of skin or other casing and boil.