Marvin Minsky: Physics is hundreds of years old. Archimedes was pretty good at it, and Galileo and Newton made major steps. And so in the 20th century, physics was several centuries old. Biology came later, but there was quite a lot known. But in psychology, it’s a wonderful field which only started, a few people around 1850, and even by 1900, there weren’t very many people making good theories. Sigmund Freud, who I read when I was a child, was the only one who seemed to have a kind of architectural idea of the mind is made of many parts, and he made speculations about how it works.