In April 1963, Washington University, in Seattle, invited Richard Feynman, winner of the Nobel Prize for physics, to give a series of lectures on general subjects that he felt strongly about. Feynman, known as a theoretician of pure science, turned his attention not only to scientific topics but also to such matters as the relations between religious faith and reason, flying saucers, paranormal phenomena, the responsibility of the scientific community towards the rest of humanity, and the trust that citizens should place in politicians. Feynman is a brilliant speaker and these lectures amply illustrate his sense of humour, his mordant wit, and his independence of mind.Thanks to this unique document, the French public will be able to discover Feynman in his own words.Translated from English. Winner of the Nobel Prize for Physics Feynman was awarded the Nobel Prize in 1965 for his work on quantum electrodynamics. As a young man during World War II, Feynman played an important part in the Manhattan Project. Later, he helped to explain the accident on board the U.S. spacecraft Challenger. He is known both for his teaching as for his significant contributions to science, which include the invention of diagrams that revolutionised the way physicists reason and make calculations.