Douglas Hofstadter is a professor of cognitive science at Indiana University, with connections to several departments including Computer Science and Psychology. A math major at Stanford, he did his Ph.D. in physics at the University of Oregon. He explored number theory using computers in the early 1960's, and fell in love with "experimental mathematics". He never studied geometry at all, but somehow fell in love with it purely on his own in 1992. His love affair with Euclidean and other geometries (including Euclidual, its dual with respect to the self-dual projective geometry), mediated in large part through Geometer's Sketchpad, has been most ardent. He is deeply involved with triangle centers and their complex interrelationships, and has taught several courses on geometry and discovery, called "Circles and Triangles: Diamonds of Geometry" (or "CaT:DoG"). He is working on a book on these topics.