The different branches of algebra and analysis which have been investigated are so numerous that it would be quite impossible to give an approximately exhaustive representation even only of the most important problems, within the limits of the time allowed to me. I, therefore, have confined myself to the minimum admissible number, namely one.
Congress of Arts and Science: Universal Exposition, St. Louis, 1904, On Present Problems of Algebra and Analysis (p. 518), Houghton Mifflin & Co. 1905