 This entry has focused on broad themes pursued throughout Nietzsche’s writing, but most philosophically sophisticated commentary on his work has been devoted to the explication of certain core doctrinal commitments, which Nietzsche seems to rely upon throughout, but which he does not develop systematically in his published works in the way typical for philosophers. Some of these doctrines, like the idea of the eternal recurrence of the same, are described as “fundamental” by Nietzsche himself (EH III, Z, 1), but are formulated in surprisingly cryptic or metaphorical ways—and discussed, or even mentioned at all, much more rarely than one would expect given the importance Nietzsche placed on them. Others are alluded to more frequently, but raise theoretical questions that would normally call for careful philosophical development that is largely absent in Nietzsche’s books. Commentators have therefore expended considerable effort working out rational reconstructions of these doctrines. This section offers brief explanations of three of the most important: the will to power, the eternal recurrence, and perspectivism.