The distinguished atomic physicist combines conversations linked with modest autobiography to introduce his readers to the metaphysical implications of atomic theory. Though it would be helpful of course to know something of the field, no great scientific sophistication is required. Heisenberg's discussion of the theories themselves is graciously simplified and goes only so far as necessary to indicate the chronology and the more general intellectual problems presented at each critical juncture. The conversations center on the epistemological difficulties of atomic investigation: from his first baffled schoolboy encounter with Plato's Timaeus and an unsatisfactory diagram of atoms held together by hooks and eyes, through the apparent contradictions of quantum mechanics, to the emergence, with considerable help from Neils Bohr, of a subtle ontological affirmation. They are more and less easily grasped, but Heisenberg's method of historical reconstruction is most helpful in giving us the benefit of early exploratory analogies, etc., which are subsequently refined. The range is a great deal wider than this may suggest, however, into religion, biological speculation, and most importantly politics and ethics. The latter themes dominate during the war years when Heisenberg took Planck's advice to remain in Germany (against Fermi's, to emigrate) and was consequently obliged to do atomic bomb research for Hitler. Though the later dialogues are more sympathetic than one might imagine, they are understandably far less assured and convincing than the others. Participants include Einstein, Planck, Dirac, but the dominant presence is Niels Bohr, whose beautifully affectionate depiction is one of the book's great assets.