This book, composed of material prepared for the Silliman Lectures by john von Neumann before his death, represents the views of one of the greatest mathematicians of the twentieth century on the analogies between computing machines and the living human brain. He concludes that the brain operates in part digitally, in part analogically, but uses a peculiar statistical language unlike that employed in the operation of man-made computers. At the time of his death in February 1957, Dr. von Neumann, renowned for his theory of games and his work at the Electronic Computer Project at the Institute for Advanced Study, was serving as a member of the Atomic Energy Commission. A year earlier, he had written: "I still cherish the hope that I will be able to deliver hte Silliman Lectures as planned." These plans were never brought to fruition, however, and the manuscript for this book constitutes the last writing to come from him.