In early summer 1925, at the age of twenty-three, Werner Heisenberg created quantum mechanics. With this, he gave the quantum hypothesis, which had been discovered by Planck in 1900, applied by Einstein to the theory of light in 1905, and by Bohr to the theory of atomic structure in 1913, and further developed by Heisenberg's teachers Sommerfeld and Born, its definitive form, which has since only been elaborated upon but does not need to be fundamentally changed. Heisenberg suffered from hay fever, so he often escaped during the Whitsun holidays to areas where the air was not filled with pollen. In 1925, he went to Helgoland, and in two weeks, he mathematically worked through the theory he suspected. When I began studying with him four and a half years later, he took me with him for a new stay in Helgoland during Whitsun 1930. There, he told me, "Back then, five years ago.".