Why is Nietzsche's thought and philosophy still regarded as relevant today? There are a large number of possible answers to a question like this, but one of the most important and persuasive is that Nietzsche questioned and discussed the nature, character and value of our values. Nietzsche frequently turns other questions such as epistemological and ontological ones into axiological ones, making values pivotal in his thought. It is possible to argue that the revaluation of all values is both the most important and today the most relevant of Nietzsche's main philosophical themes and projects. Furthermore, the theme is intimately involved with what Nietzsche regarded as his most important work, his magnum opus (that he called his Hauptwerk), for a long period called The Will to Power but later Revaluation of All Values.