über Hendrik Antoon Lorentz in "Professor H. A. Lorentz as researcher", S. 1, Rotterdam, 1923, zitiert in: Paul Ehrenfest, Collected scientific papers, 1959, North-Holland Publishing Company, S. 471-478
Original engl.: "When we read the name H.A. Lorentz - what sort of picture does this name evoke in us, what do we see in our minds? Whoever knows Lorentz personally will feel: first of all it is his eyes! […] they shine at us, eternally young, full of serenity an benevolent wisdom and with loving understanding - and all that is seasoned by a smile which by its amiable irony at once relaxes exaggeration of whatever sort."
Paul Ehrenfest Zitate und Sprüche
Paul Ehrenfest: Zitate auf Englisch
“You will get your difficulties with the point electron.”
as quoted by Hendrik Casimir in an interview http://www.aip.org/history/ohilist/4550_1.html by Thomas Kuhn, Léon Rosenfeld, Aage Bohr and Erik Ruedinger at the Institute for Theoretical Physics, Copenhagen, 5 and 6 July, 1963.
Attributed
about the theory of general relativity, in a letter dated November 24, 1919, to Albert Einstein.