Obituary notices

At Düsseldorf, on the night of April 25th, 1849, there was anxiety in the house of the secretary to the Regierungspräsident. Without, the cannon thundered on the barricades raised by the insurgent Rhinelanders against their hated Prussian rulers. Within, although all had been prepared for flight, there was no thought of departure; on that night was born a son to the stern Prussian secretary. That son was Felix Klein. His birth was marked by the final crushing of the revolution of 1848; his life measured the domination of Prussia over Germany, and typifies all that was best and noblest in that domination; with his last illness came the consummation of its downfall. Gradually, but irresistably, the nervous malady of which from time to time he had had serious warnings, mastered and prostrated him. It was, he thought, partly due to heredity on his mother’s side, partly to his own unbridled expenditure of mental energy—an energy which remained so indomitable that, even during the last two years of his life, when he lay helpless, becoming daily weaker and weaker in body, he never complained, and remained clear to the end, working and even correcting proof-sheets. At half past eight on the evening of Monday, June 22nd, 1925, he passed painlessly away. 2. Few mathematicians have left such ample material for forming an opinion of their life and work as Felix Klein. We have his life, written by his own hand two years before his death. We have his Collected Mathematical Papers, in three volumes, thoroughly revised by himself, and interspersed with supplementary notes and introductory articles of an autobiographical character. We already have the greater part of his mathematical lectures in print, lectures which had for many years enjoyed a considerable publicity in lithographed form; we have even a faithful record of lectures given by him in the years just preceding his death, carefully annotated by his colleague and successor, Professor Courant.