Felix Klein
…Klein’s life had not been without its inner tragedy. The power of synthesis had been granted to him to an extraordinary degree. The other great mathematical power of analysis had been to a certain extent withheld. His ability to bring together the most distant, abstract parts of mathematics had been remarkable, but the sense for the formulation of an individual problem and the absorption in it had been lacking. “He was like a flier who, soaring high over the world, discovers and looks over new fields … but cannot land his plane in order to take actual possession, to plow and to harvest.” Perhaps Klein had himself been unaware of this deep schism… Certainly he had perceived “that his most splendid scientific creations were fundamentally gigantic sketches, the completion of which he had to leave to other hands.”