Herr Otto Lilienthal seems to have been the first man who really comprehended that balancing was the first instead of the last of the great problems in connection with human flight.

Speech to the Western Society of Engineers (18 September 1901); published in the Journal of the Western Society of Engineers (December 1901); republished with revisions by the author for the Annual Report of the Board of Regents of the Smithsonian Institution (1902)