The book under review was written neither by a mathematician nor by a historian. The author, a Polish reporter and journalist, writes well about mathematics without using any mathematical symbols. Professional mathematicians will spot a few technical errors of the type that inevitably creep into exposition at this level. Such small mistakes in mathematical details can easily be forgiven because the author does a good job of capturing the flavor of early functional analysis and its creators. The book suffers more from the lack of a historian's perspective than from an absence of mathematical expertise.
Some events described in the book cry out for more explanation.
Before capturing the Polish university town of Lvov, where Banach lived and worked, German officials compiled a list of prominent professors, scientists, and writers in Lvov who would be executed. One night shortly after German soldiers had entered Lvov, SS units murdered forty leading intellectual figures in Lvov without even the pretense of trials. But Banach was untouched by the Nazi death squads. An alert reader will wonder why Banach, who at this time was President of the Polish Mathematical Society and a Dean at the university, was not among the intellectuals marked down for liquidation. Unfortunately the author does not comment on the apparent disparity between his description of Nazi plans to crush Polish intellectual life and the survival of Banach, Poland's most influential mathematician.