Includes a new introduction by the author and a foreword by Douglas Hofstadter. Alan Turing was the outstanding Cambridge mathematician who led the decryption of the German Enigma codes and transformed World War II. But his vision extended far beyond this critical achievement. Before the war, he had formulated the concept of the universal machine, and in 1945, he transformed this into the first design of a digital computer. Turing's insightful proposals for the digital age advanced into a perspective on Artificial Intelligence. However, in 1952, his homosexuality rendered him a criminal, and he suffered humiliating treatment. In 1954, at the age of 41, Alan Turing committed suicide, and one of Britain's greatest scientific minds was lost.