Hans Jonas here rethinks the foundations of ethics in light of the awesome transformations wrought by modern technology: the threat of nuclear war, ecological ravage, genetic engineering, and the like. Though informed by a deep reverence for human life, Jonas’s ethics is grounded not in religion but in metaphysics, in a secular doctrine that makes explicit man’s duties toward himself, his posterity, and the environment. Jonas offers an assessment of practical goals under present circumstances, ending with a critique of modern utopianism.