D O C . 7 5 N O B E L L E C T U R E 135 Published in Les Prix Nobel en 1921–1922 (Stockholm: Norstedt & Fils, 1923), pp. 1–10 (indepen- dent pagination). It was also published as a separate publication, presented here. The manuscript was completed on 8 July 1923 (see Doc. 76). Einstein received the news that the 1921 Nobel Prize had been awarded to him while traveling to Japan in November 1922 (see Christopher Aurivillius to Einstein, 10 November 1922 [Vol. 13, Doc. 384]). Because of his trip he was unable to attend the official awarding ceremony on 10 Decem- ber 1922. In March 1923 it was decided that he would deliver his Nobel Prize lecture on 11 July 1923 at the Skandinaviska Naturforskaremötet in Gothenburg (see Svante Arrhenius to Einstein, 17 March 1923, and Einstein to Svante Arrhenius, 23 March 1923 [Vol. 13, Docs. 445 and 449]). Einstein makes the same point on p. 2 of his 1921 Princeton lectures (Einstein 1922c [Vol. 7, Doc. 71]). He also makes a similar point in Doc. 321, but adds that the concepts of a theoretical system refer to the empirical facts only as a whole, rather than individually see Howard 2014 for discussion This giving of physical significance to the concepts of a coordinate system and of motion of mat- ter is worked out in more detail in Einstein 1922c (Vol. 7, Doc. 71), pp. 3–4. Tullio Levi-Civita, Hermann Weyl, and Arthur Eddington. See Einstein 1923s (Doc. 123) for Einstein’s summary of their ideas see also note 8. Later that year Einstein claimed that observations confirmed the existence of gravitational red- shift (see Doc. 182). See also Earman and Glymour 1980 for a historical overview of the attempts to find gravitational redshift. See Mach 1897 for Ernst Mach’s critique of Newton’s concept of absolute space and his alter- native interpretation of inertia (“Mach’s Principle”). See also Einstein 1916c (Vol. 6, Doc. 29), Ein- stein’s obituary of Mach, for Einstein’s assessment of the importance of Mach’s work. See also Vol. 8, the editorial note, “The Einstein–De Sitter–Weyl–Klein Debate,” pp. 351–357, for more on Einstein’s view of the role of Mach’s principle in cosmology. See Levi-Civita 1917, in which the notion of parallel displacement was introduced. See Weyl 1918, 1919, 1923, for Weyl’s unified theory. See also Einstein’s critique of Weyl in Ein- stein 1918g and in his correspondence with Weyl in Vol. 8. Eddington’s unified theory is presented in Eddington 1921. With Weyl’s theory it had in common that it took the affine connection as the central quantity instead of the metric. Initially, Einstein was skeptical about Eddington’s work (see Einstein to Hermann Weyl, 5 September 1921 [Vol. 12, Doc. 230] and 6 June 1922 [Vol. 13, Doc. 219]), but he later changed his mind and wrote three papers elaborating on Eddington’s ideas (Einstein 1923e [Vol. 13, Doc. 425], and Einstein 1923h, 1923n [Docs. 13 and 52]). For an analysis of Einstein’s reaction to Eddington’s work, see Stachel 1986.