 Poincaré is also famous for his 1904 conjecture concerning the topology of three-dimensional spheres which remained one of the major unsolved problems in mathematics until the Russian mathematician Grigori Perelman succeeded in demonstrating it nearly one hundred years later. Poincaré lectured on contemporary mathematical physics for years and was very much abreast of current developments. Popularizer of science, pedagogue, man of letters, he became an icon of the popular press (see Rollet 2017, XLVI). In all he published over five hundred scientific papers and over thirty books. He died July 17, 1912 in Paris from a blood clot to the brain which was a complication of surgery, survived by his wife and their four children (see Rollet 2000, Boutroux 2012, Ginoux and Gerini 2012).