I N T R O D U C T I O N T O V O L U M E 1 5 l x x x i i i possess wavelike properties. His adviser, Paul Langevin, sent a copy of the disser- tation to Einstein (see Vol. 14, Introduction, p. lxxxiv), who discerned its revolu- tionary nature and responded on 16 December 1924: “The paper by De Broglie greatly impressed me. He has lifted one corner of the great veil” (Vol. 14, Doc. 398). On the same day he also wrote to Lorentz: “I think this is the first weak ray to cast light on this worst of all our physical puzzles (i.e., the Bohr-Sommerfeld quantum rule)” (Vol. 14, Doc. 399). Einstein drew on De Broglie’s ideas in his pa- pers on the quantum theory of the ideal gas, especially in Einstein 1925f, where he wrote: “One then sees that to such a gas a scalar wave field can be assigned,… it seems as if a wave field were associated with every process of motion” (Vol. 14, Doc. 385). It now appears that Schrödinger’s wave mechanics was at least partly inspired by his discussions with Einstein on Bose-Einstein statistics and the link that Einstein had forged between quantum statistics and De Broglie’s idea of matter waves. Their remarkably rich exchanges on the topic began on 26 September 1925. Einstein wrote how much he appreciated Schrödinger’s recent publications on quantum sta- tistics but then spent most of the letter criticizing Max Planck’s recent paper on the same topic and asking for Schrödinger’s opinion (Doc. 80). The ensuing letters (Docs. 101, 103, 107, 108, 123, 174) center on the various ways of deriving and in- terpreting quantum statistics, as well as on the observation that the particles derived by it are “squatting together,” as Schrödinger puts it—the phenomenon now known as Bose-Einstein condensation (Doc. 101). Schrödinger saw himself as only work- ing out Einstein’s original idea (in Doc. 80) and suggested a joint publication. Ein- stein answered: “I just don’t know whether I should count as a coauthor since after all you did all the work I would feel like an ‘exploiter,’ as the socialists like to put it so beautifully” (Doc. 108). To this Schrödinger replied: “The idea of regarding you as an ‘exploiter’ would not have occurred to me even in jest. To continue with the sociological work analogy, one could rather say: When a sovereign builds, car- ters have plenty to do” (Doc. 123), a reference to Goethe and Schiller’s Xenien, in which the two poets refer to Immanuel Kant as the king and to his interpreters as the carters. How Einstein could have resisted such an invitation we shall never know. He presented Schrödinger’s sole-author paper to the Prussian Academy on 7 Janu- ary 1926, he himself having supplied an abstract (Doc. 153). Schrödinger was getting closer to becoming royalty himself. Three weeks before Einstein presented Schrödinger 1926a to the Academy, Schrödinger submitted his paper “On Einstein’s Gas Theory” to the Physikalische Zeitschrift (Schrödinger 1926b). It was soon followed by his first paper on wave mechanics, “Quantization as an Eigenvalue Problem. First Communication,” published in Annalen der Physik