Each week we teach expressions often used in American English . We explain how to use them and sometimes where they come from . But do not take my word for it . You will soon see for yourself that our teaching methods work ! Or as we like to say : The proof is in the pudding . This expression means that the best way to find out if something is good or successful is to test it yourself . The Oxford Dictionary of Quotations claims this expression was first used in early 14th century . As with many expressions , this one has changed over the years . People back then said it this way : the proof of the pudding is in the eating . Knowing the full original version is important when explaining this expression . Also important is understanding the two main words in the sentence : pudding and proof . You may ask , “What is that ?” Well , the answer depends on whether you are using American English or British English . However , if you order pudding at a restaurant in London and expect a soft , sweet dessert , you could be in for a big surprise . In Britain , pudding is a savory meat dish . In fact , the British would call our sweet dessert pudding a custard . Now , the British do have sweet puddings such as their sticky toffee pudding and Christmas pudding . But they are solid puddings made with a lot of dried fruits . Again , nothing like an American milk-based pudding . And their savory puddings are even more different . Centuries ago in Britain , people combined different meats , placed them into an animal membrane , or tissue , and then made a kind of sausage . They covered the meat-filling with a soft shell made from flour and meat fat . Then they would cook the pudding by boiling or steaming it . Like I said , the two puddings are very different . But it is this traditional English “pudding ,” that gives us the expression : “The proof is in the pudding .” And that brings us to the second word : proof . Today “proof ” means something that shows that something else is true . A similar word is evidence . But centuries ago “proof ” meant to test something . So we could say the expression this way : “The test of the pudding is in the eating .” And now , another question . Why is testing the pudding important ? Well , to answer this we need to go back to the main ingredient in the British pudding : sausage . Centuries ago , there was no refrigeration to keep food cool and fresh . So meat would often go bad . If you weren't careful , you could get “botulism ,” a food-borne sickness . And the root word of botulism , botulus , is the Latin word for – you guessed it – sausage . So , testing the pudding was the only way to really know if the meat was still good to eat . So , that is the story of this expression . Now , let's talk about when and how to use it . The proof is in the pudding is very common . I would feel at home using it with an office supervisor , strangers or people much older than me . Other ways to say this expression are : “I'll believe that when I see it ” and “I'll be the judge of that !” These are both a little more casual . To best explain how to use it , I'll give you a few examples . In this first one , a woman's car won't start . So , her friend is helping to fix it . Or is he ? And then after I connect this wire here … your car will be fixed . Are you sure ? That doesn't look right . Yes , I'm sure ! Well the proof is in the pudding . Let's start it up ! Yeah , I didn't think that was right . Here , give me the tools . In this next example , a team leader is talking to a group of computer programmers . They have been working hard on a new product and are preparing to test it . All right , team . This is it . We have written the program and designed the website . Tomorrow we run our first live test . We have worked so hard ! I know you've all worked really hard . But the proof is in the pudding . If it doesn't work , be prepared to work over the weekend to fix it .