E I N S T E I N ’ S L E C T U R E A T K Y O T O U N I V E R S I T Y 6 2 7 In 1969, Gerald Holton argued that despite the fact that many textbooks and other ac- counts of the theory of relativity assigned crucial importance to the Michelson experiment, documentary evidence for its role as a crucial experiment in Einstein’s early intellectual de- velopment was rather meager and, at best, indirect (Holton 1969, 1988, ch. 8). Einstein’s Kyoto lecture itself was not discussed by Holton. It was Tetu Hirosige who added it to the list of documents relevant to the historical discussion (Hirosige 1976, pp. 51–57). An incomplete English translation of Ishiwara’s account of Einstein’s Kyoto lecture was published by Tsuyoshi Ogawa in 1979 (Ogawa 1979), followed by a complete translation by Yoshimasa A. Ono (Ono 1982). In their translations, Einstein appears to have told his audience that he did know of Michelson’s experiment early on, and that it had indeed deci- sively influenced his thought—in contradiction to some later recollections by Einstein (Shankland 1963, pp. 48, 55). In 1999, Ryoichi Itagaki challenged both Ogawa’s and Ono’s translations of the relevant passage—consisting of only two sentences—and suggested an alternative translation (Itagaki 1999).[7] In Itagaki’s interpretation, the Japanese text sug- gests that Einstein did not know of Michelson’s experiment as a student, an assessment con- gruent with with Holton’s original discussion. Another English translation by Seiya Abiko followed Itagaki’s interpretation for the first sentence in the passage, but disagreed with his translation of the second (Abiko 2000, p. 13). In order to facilitate future discussion of the issue, we present here (in Doc. 399) the text of Ishiwara’s notes as first published in Kaizo, together with a new English translation, pre- pared for this volume by the editors in cooperation with Masako Ohnuki, on the basis of a draft translation by Ryoichi Itagaki and Michel Janssen. Apart from his correspondence with Mileva Maric (see Vol. 1), there are very few extant primary documents that could shed light on Einstein’s early explorations and thoughts that led to the formulation of the special theory of relativity. The Kyoto lecture, despite being an indirect source, constitutes the most explicit reflection of Einstein’s thoughts by 1922 on the genesis of the theory of relativity. It is, however, not the first historical reflection on Ein- stein’s part about the genesis of the theory of special relativity. A positive role for the Mi- chelson experiment, according to Einstein’s own recollection, can also be inferred from the comments he had made a year earlier, when talking about the subject to an audience of teachers in Chicago.[8] Even as early as 1916, Einstein reflected on the role of the Michel- son experiment in his conversations with Max Wertheimer. Unfortunately, here again, the evidence is indirect. Einstein’s recollections were the basis for a chapter in Wertheimer’s book on Productive Thinking, which was published in 1945 after Wertheimer’s death.[9] V The Kyoto lecture gives us an account not only of the genesis of the special theory of relativity but also about the path toward general relativity. Here again, the document pro- vides one of the most explicit recollections by Einstein on the development that led to the theory of general relativity. This development, however, is amply documented by primary