xxxviii INTRODUCTION TO VOLUME 1 In a letter to Maric written before Lieserl's birth, Einstein took for granted that the child would join them after he began work at the Patent Office. But in fact Lieserl did not join them. A later Einstein letter indicates that she survived an attack of scarlet fever in 1903. Beyond that, no further informa- tion about her fate has yet been found, in spite of our efforts to locate records in Yugoslavia. Most of the events of a personal nature documented in this volume are not mentioned in Einstein's later reminiscences. In his Autobiographical Notes, he wrote: "[D]as Wesentliche im Dasein eines Menschen von meiner Art liegt in dem was er denkt und wie er denkt, nicht in dem, was er tut oder erleidet" (Einstein 1979, p. 30). This statement, at first sight, discourages any attempt to understand Einstein's personality or achievements by a reconstruction of the course of his life. But Einstein himself emphasized the process that brought him to this point of view: "Bei einem Menschen meiner Art liegt der Wendepunkt der Entwicklung darin, dass das Hauptinteresse sich allmählich weitgehend loslöst vom Momentanen und Nur-Persönlichen und sich dem Streben nach gedanklicher Erfassung der Dinge zuwendet" (ibid., p. 6). How and when did this turning point in his development take place? In some of the documents presented here, unmistakable signs of the in- tensity of Einstein's commitment to scientific work and of his turning away from the "Momentanen und Nur-Persönlichen" are already visible. At the age of eighteen, for example, he wrote: "Die angestrengte geistige Arbeit & das Anschauen von Gottes Natur sind die Engel, welche mich versöhnend, stärkend & doch unerbittlich streng durch alle Wirren dieses Lebens führen werden" (Doc. 34). To evaluate these words, it is important to know the circumstances under which he wrote them-an emotional crisis occasioned by the ending of his first serious romance. A few years later, Einstein's efforts to find a place in a university, or even in a secondary school, ended in complete failure, and he was forced to accept a temporary position as a tutor. Yet he never lost a sense of self-confidence that enabled him to write, after a clash with his employer: "Es lebe die Unverfrorenheit! Sie ist mein Schutzengel in dieser Welt" (Doc. 127). In try- ing to form a picture of the development of his peculiar genius, one should no more ignore such events and his reaction to them than one would dis- regard evidence of his scientific preoccupations during these years. Even during moments of personal crisis or despair at his inability to find a position, Einstein never wavered in his devotion to scientific work. This volume provides important new material about Einstein's intellectual devel- opment. His sister Maja stressed his precocious talent in mathematics (see MWE, this volume, p. lxi), and Einstein's grades and Aargau school examina-