l x x I N T R O D U C T I O N T O V O L U M E 1 3 At a special session of the Royal Academy of Exact, Physical, and Natural Sciences, held in the presence of King Alfonso XIII, Einstein was made a corre- sponding member of the academy. A “tea of honor” in his name was held after- wards, attended by the Madrid intelligentsia, as was a special session of the Mathematical Society. On 7 March, Einstein met with King Alfonso and the Queen Mother. That eve- ning, a reception in Einstein’s honor was held at the German ambassador’s resi- dence. The following day he received an honorary doctorate from the Universidad Central and gave a fourth lecture at the Ateneo de Madrid, a literary-scientific club, on the philosophical implications of relativity. He also found time for three visits to the Prado, an excursion to Toledo—which he described as “[o]ne of the finest days of my life”—and a day trip to El Escorial and the Castle of Mendoza. The Ger- man ambassador was pleased with the outcome of Einstein’s visit. Reporting back to Berlin, he claimed that no other foreign scholar had been accorded such an en- thusiastic welcome. Einstein’s final stop was Zaragoza (Saragossa) in Aragon. Upon his arrival on 12 March, he was met by a delegation from the University of Zaragoza, by the Ger- man consul, and by the mayor. He gave two lectures in French at the Faculty of Medicine and Science, toured the city, and attended a banquet at the German con- sul’s residence. He departed Zaragoza on 14 March, spent a day in Barcelona with- out any official obligations, and then traveled by train to Zurich. All in all, he had been absent from Berlin for five and a half months. Einstein had thoroughly enjoyed the isolation on board the ship and repeatedly noted in his diary how much he cherished the peace and quiet of the wide open sea. At the beginning of his return trip to Europe, he wrote to Svante Arrhenius: “And how conducive to thinking and working the long sea voyage is—a paradise without correspondence, visits, meetings, and other inventions of the devil!” (Doc. 420). But the intensity of the Japan tour left Einstein with conflicting emotions as to whether he would embark on such an endeavor again in the future. By mid- December he wrote to his sons from Kyoto: “I have decided definitely not to galli- vant around the world so much anymore but am I going to be able to pull that off, too?” (Doc. 400). Hans Albert had passed his Matura examinations and had enrolled at the Eidgenössische Technische Hochschule, Albert Einstein’s alma mater, as a first semester engineering student in September 1922. Prior to that, he had been very eager to participate with his father in the voyage to the Far East (Docs. 246 and 248). But Einstein did not want his son to delay university enroll- ment, and, from Japan, softened the boy’s disappointment by writing that the stren- uous schedule of official engagements would not have allowed any free time with him, and that his studies were of greater importance than the trip. And now that the