In October 1895, the most mysterious mechanisms of the mind suddenly clicked into place for Sigmund Freud. The Viennese psychoanalyst reported his discovery in a breathless letter to his colleague and confidant, Wilhelm Fliess. After "an industrious night", he wrote, "the barriers suddenly lifted, the veils dropped, and everything became transparent – from the details of the neuroses to the determinants of consciousness." The result of that night was one of Freud's earliest works, the forbiddingly titled Project for a Scientific Psychology.