Here’s a very useful site called, Quote Investigator. As its name states, the site is dedicated to investigating the origins of English-language quotes. I stumbled upon it trying to verify the origins of one of my all-time favorite quotes, usually attributed to either Oscar Wilde or Winston Churchill: “I am a man of simple tastes. The very best always satisfies me”.
It’s interesting to see how quotes are often distorted over time, even within thir own generation. This is an even bigger problem if the quotes weren’t in print, but attributed by others, as is the case with the one above.