ABSTRACT
It was in author's second year in Gottingen that my scientific future was determined, not by his own deliberate choice, but by a series of events in which he was involved. At that time Klein's interest in the physical and technical application of mathematics was at its height and infected the other professors, even mathematicians as 'pure' as Hilbert and Minkowski. One afternoon a week was fixed for what we called the 'Bonzen-Spaziergang'. Felix said that the author was not interested in what he was going to do. The author braced himself and asked Felix whether, should he succeed, Felix would accept his work as a doctor's thesis. The formal graduation was six months later, in absentia, as the author was then serving in the army and could not attend. He was, a young doctor of philosophy, a young man of means and prospects the world lay before him to be conquered.
