Do I need to cite the source of a famous quote in my thesis? I'm writing part of my Computer Science PhD and I'd like to know whether it is generally acceptable to have a reference to a famous quotation by a famous person without citing a source. For example,


  "Program testing can be used to show the presence of bugs, but never to show their absence!" - Edsger W. Dijkstra
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.