Book excerpt: In this series of 15 essays, which won the Letterstedt Prize, Sweden's equivalent of the Pulitzer, distinguished cell biologist George Klein shares his considerable insights on science and on human nature. Organized loosely as "The Wisdom and Folly of Scientists," "Journeys," "Viruses and Cancer," and "La Condition Humaine," the essays range from lucid explanations of biological and genetic processes to personal remembrances and studies of famous scientists to discussions of the complicity of science and medicine in the Nazi extermination camps.