Frases de Solomon Lefschetz

[Carl C. Gaither, Alma E. Cavazos-Gaither, Gaither's Dictionary of Scientific Quotations: A Collection of Approximately 27,000 Quotations Pertaining to Archaeology, Architecture, Astronomy, Biology, Botany, Chemistry, Cosmology, Darwinism, Engineering, Geology, Mathematics, Medicine, Nature, Nursing, Paleontology, Philosophy, Physics, Probability, Science, Statistics, Technology, Theory, Universe, and Zoology, https://books.google.com/books?id=zQaCSlEM-OEC&pg=PA29, 5 January 2012, Springer Science & Business Media, 978-1-4614-1114-7, 29]