Nietzsche’s campaign against morality began with Daybreak, Thoughts on the Prejudices of Morality, a major book that still remains underappreciated. This monograph explores the structure and coherence of Daybreak in order to highlight its philosophical ambition: namely, to explore the real effects of illusory representations and beliefs that are so deeply rooted in human nature and culture. This task involves not only deconstructing many prejudices, but even more so establishing the very logic underlying them. Only a careful examination of the psychological, physiological and social mechanisms underlying this logic of prejudice will enable us to correctly evaluate its consequences and scope.