1 4 2 D O C U M E N T 1 2 1 M E S S A G E T O L O R E N T Z 121. “Message to Mr. Hendrik Antoon Lorentz on the Occasion of the Fiftieth Anniversary of His Doctorate on 11 December 1925” [Einstein 1926h] Completed on or after 3 December 1925[1] Presented 17 December 1925 Published 20 January 1926 In: Preußische Akademie der Wissenschaften (Berlin). Physikalisch-mathematische Klasse. Sitzungsberichte (1925): 598. Dear Colleague, The Prussian Academy of Sciences conveys to you, as a corresponding member and as one of the most gifted scientists of the present day, its cordial congratulations.[2] Your influence on the development of physics has been such a decisive one that nobody can say when science would have correctly recognized the influence of matter and its motions on electromagnetic and optical processes without your research. By continuing Maxwell’s lifework in a consistent way, you not only explained the relations of matter to the electromagnetic field but thereby also supplied the basis for relativity theory and electric theory of matter. Your work is of such admirable completeness that one can summarize its axiomatic basis in a single statement: Maxwell’s equations of empty space are valid everywhere and matter acts electromagnetically solely in that its smallest particles are carriers of electric charges. Based on this assumption, you have derived an almost immeasur- able abundance of consequences that have been confirmed by experience. For about 20 years we have known that your grand electrodynamic system does not signify the ultimate truth, that it does not encompass those features of reality which we summarize under the term quantum theory. But the Maxwell-Lorentz theory still serves as the most important tool for the probing endeavors of our times to come closer to the nature of elementary processes. You yourself crucially con- tributed to this more recent development with a clear and general proof of the fail- ure of the so-called classical theory as well as with derivations of important individual results you dedicated yourself to individual problems always with the