Little could be more obvious than that the mere desire for the world to be a certain way just does not mean that it is so. The 19th-century philosopher Friedrich Nietzsche believes that the philosophical tradition starting with Plato confuses metaphysics, our theories about what there is in the world, with what we hope or fear the world will be like. If Nietzsche is right, then our fear-and-hope-ridden beliefs about the world will inevitably no longer be believable, because they aren't true. If we can't believe in them, then they will no longer be useful in justifying our struggles for prosperity. The only fungible option, it seems, is to look at the world as it is. The rub is that the world is so often distressingly different than the way any sane person would want it to be. This is the dilemma of nihilism, a philosophical challenge that Nietzsche uncovered toward the end of his philosophical career and never fully resolved. In Louis Russell's follow-up to Spinoza's Science: The Ethics of Knowledge, Russell explores, explains, and expands upon the most important concepts that informed the later work that Nietzsche left incomplete.