In this pathbreaking work of intellectual and cultural history, James M. Glass provides a provocative new answer to the questions that bedevil us to this day: How and why did so many ordinary Germans participate in the Final Solution? And how did they come to regard Jews as less than human and "deserving" of extermination? Glass, a leading scholar of political psychology and political theory, argues that the answers lie in the rise of a particular ethos of public health and sanitation that emerged from the German medical establishment and filtered down to the common people. Building his argument on a trove of documentary evidence, including the records of the German medical community and of other professional groups, he traces the development, in the years following World War I, of theories of "racial hygiene" that singled out the Jews as an infectious disease that had to be eradicated if the Aryan race were to survive - as "life unworthy of life," in the words of Nazi propagandists and German scientists. In their zeal to preserve the health of the German Volk, he observes, the people of the Third Reich became willing participants in the Final Solution, thinking of themselves not as executioners, but as highly motivated actors in a culture-wide sanitation project with the objective of purifying blood and genes.