It is now a little more than 11 years since the idea of writing a personal and scientific biography of H. A. Kramers took hold of me. A few days earlier I had been lecturing, in a course on field theory, on the renormalization proce- dures of relativistic quantum field theory. Since the students had considerable trouble understanding the physical basis of the procedure, at the end of the lecture T explained that renormalization is not an exclusive...