Crick, who dominated the field of molecular biology, was jointly responsible for discovering the structure of DNA, as well as setting out the principles of the genetic code. Perutz (his PhD supervisor), Kendrew, Sanger and Klug were close colleagues, with Watson and Brenner his key collaborators. Wilkins (who shared the Nobel prize) was a friend despite professional tensions, but Crick thought Franklin too cautious for her own good. His many friends and correspondents included Delbrück, Pauling, Haldane, Waddington, Bernal and Popper. Gamow joked that having had a lot of practice decoding proteins, he had almost succeeded in decoding Crick’s handwriting.