In a note from 1887, Nietzsche maintains that metaphysical beliefs are the products of ressentiment, and not the fruits of philosophical insight that metaphysicians take them to be. I aim to reconstruct Nietzsche’s attempt to explain metaphysics through an appeal to this distinctively human variety of vengefulness. By a metaphysical belief, Nietzsche understands a belief about entities that cannot be objects of human sensibility. Such entities form what he calls a “true world” – a realm of being that is both opposed to and more valuable than the realm of becoming that is present to us through the senses. I argue that, for Nietzsche, metaphysical beliefs satisfy ressentiment not simply by generating the value judgment that the sensible world is less valuable than the true world, but by generating in addition the judgment that this world ought to perish and the fantasy of that perishing. Thus, metaphysical belief is a variety of philosophical pessimism. I conclude by showing that Nietzsche explains the content of the metaphysical concepts “true” and “apparent” in the same way that he explains the content of the ethical concepts “good” and “evil.” In both cases, our thinking becomes moral as the result of a vengeful revaluation of values.