Reinhard Siegmund-Schultze’s *Mathematicians Fleeing from Nazi Germany: Individual Fates and Global Impact* very successfully addresses the themes given in the subtitle, themes which concern not just the nature of the international mathematical community in the wake of the Nazi horrors of the 1930s and '40s, but, indeed, the entire modern mathematical world itself. Siegmund-Schultze, a professor of the history of mathematics in Norway, has carried out this important and informative research with meticulous care and attention to detail. He has produced a work of true historical scholarship covering four hundred pages and then some, filled with fascinating prose and supplemented by copious footnotes testifying to the weighing and sifting necessary in constructing such a cogent and grand-scale analysis. Additionally the book reads very smoothly and the inclusion of fifty-eight photographs and innumerable case-studies, covered compactly but hitting very hard, adds particular poignancy to the narrative: notwithstanding the tragic tones of *Mathematicians Fleeing from Nazi Germany* the book is difficult to put down.

For mathematicians of my age (now in my middle fifties) there is an additional reason to gravitate toward the book under review: there is a huge likelihood of personal acquaintance with refugees from Hitler’s Germany. In my case, I was taught number theory, history of mathematics, and complex analysis by Ernst G. Straus, whose family left Germany already in the early 1930s, and I was in graduate school at UCSD in La Jolla when Stephan Warschawski (one of Hilbert’s last students) still attended the weekly seminar on Julia sets run by, among others, Christian Pommerenke, visiting from Germany. Indeed, *qua* degrees of separation from victims of the diaspora precipitated by the Nazis, for almost all of us this index reads very low.

To be sure, the collection of mathematicians (and physicists, occasionally) dealt with in *Mathematicians Fleeing from Nazi Germany* includes a huge proportion of very familiar names, many in turn associated with American universities as mainstays of their evolution into major research centers in the middle part of the twentieth century. But this story is much more complex than it might at first appear. For one thing, as European mathematicians, the vast majority Jews, began to flock to the United States, carrying with them *avant garde *mathematics and established scholarship methods from the frontier, at a time when America still largely lagged behind, suspicion, jealousy, and fear — and even anti-Semitism — arose in certain American academic circles, focused on the proposition that these *émigré* scholars would displace home-grown talent and come to dominate the American mathematical scene. Says Siegmund-Schultze on p. 29 of his book: “It is striking … that until the end of the war, with the exception of a few applied mathematicians (R. von Mises, W. Prager) and the historian of mathematics, O. Neugebauer, none of the forced emigrants were called to the existing leading departments of mathematics …”

Still, as time went on and the United States’ academic scene adapted to the changes and began to make use of the incomparable opportunities extended by the presence of these refugees, the synergetic effect of this transfusion, or rather relocation, of European mathematical scholarship to the New World, coupled with the flowering of a new generation (or two or three) of young American university students, made for the ascendancy of the United States to its present position of pre-eminence in the mathematical world. Just consider in this regard the roles played by e.g. Richard Courant at NYU, Emil Artin at Princeton, Oscar Zariski at Harvard, Antoni Zygmund at Chicago, and Alfred Tarski at Berkeley. Of course, among these only Courant and Artin came from Germany itself, but all were refugees from Europe gone mad.

And it was not just the United States that came to benefit from the scholars’ exodus. Some fled to the USSR, some to Australia, a few went to South America, and so on. In the latter connection, the story of Peter Thullen is of particular interest: he settled in Ecuador, leaving in 1952 for Switzerland. *Mathematicians Fleeing from Nazi Germany* contains an exceedingly interesting appendix presenting diary entries by Thullen titled “Memoirs for My Children (1933/1988).” These writings are particularly evocative and fascinating as a first hand account, of course, but additionally Thullen was a Catholic, not a Jew, and was not directly subject to Hitler’s horrific racial laws; he was politically undesirable, however, and a former member of the Catholic Youth Movement.

Other expatriate scholars were not at risk of being targeted by Hitler’s racial laws directly; nonetheless they were targets. Some had Jewish spouses (Hermann Weyl, Emil Artin), some, like Thullen, had political pasts that were intolerable to National Socialism, and so on. A particularly interesting case is that of the superb analytic number theorist Carl Ludwig Siegel who as a pacifist simply found the horrors of Nazi Germany too much to bear from the outset, only to find himself straitjacketed by what he perceived as unbearable prudishness on the part of Mrs. Eisenhart, the wife of Dean Luther P. Eisenhart of Princeton, who evidently was bothered by the bachelor Siegel sharing digs with two female friends (one of whom was Hel Braun, later linked to Emil Artin when he had settled in Hamburg toward the end of his life). Siegel returned to Germany briefly in the 1930s, complaining about the sexual prudishness of American society, as Siegmund-Schultze puts it on p. 247. But Siegel returned (escaping *via* Norway) after hostilities started, and, as is well known, continued to do seminal mathematics at the IAS. In due course he returned to Europe however, as did a number of others. *À propos,* as already suggested, the Siegel case is in some ways very humorous, given his rather unbridled way of addressing himself, even to figures of power and authority. See p. 247 in this connection.

*Mathematicians Fleeing from Nazi Germany* comes equipped with a number of appendices, generally dealing with correspondence from the major players in the drama. The book’s last chapter, “Epiloque: The Postwar Relationship of German and American Mathematicians,” is clearly the most significant element of the work as a piece of historical scholarship: the QED at the end of Siegmund-Schultze’s discussion. Like the rest of the book, there are heroes and villains in this end-game, and many who are neither: it cannot be otherwise in a work of historical analysis. This prevalence of human ambiguity certainly describes what may well be the most touching part of the book: the case of Emmy Nöther, already so well documented in biographies and articles over the last so many years. Siegmund-Schultze’s coverage of the details of her case, replete with correspondence cited, Einstein’s benevolent role poignantly highlighted, and her touching goodness and humanity coming through, is exemplary scholarship and excellent writing.

Clearly *Mathematicians Fleeing from Germany *is first rate, both as historical scholarship and as spell-binding reading for any contemporary mathematician.

Michael Berg is Professor of Mathematics at Loyola Marymount University in Los Angeles, CA.