This is a history of his discovery of the tau lepton in the 1970s for which the author Martin Perl was awarded the Nobel Prize in Physics. He has previously described some aspects of the discovery. In 1996 in his collection of papers entitled, 'Reflections on Experimental Science,' he gave a straightforward account of the experimental method and the physics involved in the discovery as an introduction to the collection. In a 2002 paper written with Mary A. Meyer published in the journal 'Theoria et Historia Scientiarum' he used the story of the discovery to outline his thoughts on the practice of experimental science. That 2002 paper was written primarily for young women and men who are beginning their lives in science and it was based on a lecture given at Los Alamos National Laboratory.