I N T R O D U C T I O N T O V O L U M E 1 4 x x x v i i I The volume begins by bringing to a close the scientific work that Einstein had started during his trip to the Far East. In the quiet few weeks aboard the steamer that brought him back from Japan in early 1923, Einstein had worked out an idea with respect to the affine formulation of general relativity recently advanced by Hermann Weyl and Arthur S. Eddington. Soon after setting sail, he drafted a paper entitled “On the General Theory of Relativity” (Vol. 13, Doc. 417). Finding prob- lems with his argument before sending it off, he then revised the draft, setting down some calculations on the back pages of his travel diary that document his subsequent deliberations (Vol. 13, Doc. 418). He then sent the revised version, Einstein 1923e (Vol. 13, Doc. 425), to Berlin, most likely after his arrival in Suez on 31 January 1923. In his absence, Max Planck presented the paper to the Prussian Academy for publication in its Proceedings.[1] Einstein apparently continued pondering this approach. Just a couple of weeks after his arrival back in Berlin, on 12 April, he submitted to the Academy a brief note in which he recapitulated the basic equations of the theory and added a varia- tional formulation of its field equations (Einstein 1923h [Doc. 13]). A few weeks later, on 31 May 1923, he presented another paper to the Academy, in which he again took up the approach and further developed its ideas (Einstein 1923n [Doc. 52]). Just a few days earlier, on 28 May (Abs. 16), he had agreed to write an account of the theory to be published in English in Nature (Doc. 122 and Einstein 1923s [Doc. 123]). Even though by the time he was finishing Einstein 1923n (Doc. 52), Einstein had already become somewhat disillusioned with the affine approach, he nevertheless delivered a special lecture in Gothenburg on 10 July 1923 on Weyl’s and Edding- ton’s generalizations of general relativity, alongside his Nobel Prize lecture. At around that time he also agreed to write an appendix to the German translation of Eddington’s “Mathematical Theory of Relativity” (Einstein 1925a [Doc. 282]). Einstein was not the only one engaged with such ideas. After his return to Berlin, Planck informed Einstein that Ernst Reichenbächer had done quite similar work (Doc. 4). Hans Reichenbach and Eddington wrote to him and requested copies of his papers (Abs. 44 and 124). Tullio Levi-Civita thanked him for sending copies (Doc. 93), and André Metz asked about the papers, and whether he agreed with Weyl and Eddington (Abs. 365). Weyl himself informed Einstein on 18 May that he had second thoughts about a criticism of Einstein’s approach that he had included in a recent paper. Weyl had apparently sent Einstein the proofs of this paper, and now explained why he wanted to delete the relevant passages at proof stage (Doc. 30). Unfortunately, the original