Do I need to cite the source of a famous quote in my thesis?
But please don't decorate each chapter with a quote you took from a calendar. As JiK said, there are so many misattributions and misstatements around, you need to go to the source if you absolutely must use a quote. But as chapter decoration I find them silly. Okay, Knuth is allowed to do that, but until you reach the god-like status of Knuth, please refrain.