In this chapter, the author attempts to establish what is philosophically living and what is philosophically dead in Schopenhauer’s pessimism. Against the background of the intriguing the history of the terms “optimism” and “pessimism”—in debates about Leibniz’s theodicy in the early eighteenth century and the popularity of Schopenhauer in the late nineteenth century, respectively—the author points up the distinction between affirming life, which all living beings do naturally, and subscribing to philosophical optimism (or pessimism), which is possible only for reflective beings like us. Next, the author notes the significance of Schopenhauer’s claim that optimism is a necessary condition of theism and explains its bearing on his pessimistic argument for the moral unacceptability of suicide. The chapter concludes that Schopenhauer’s case for pessimism is not conclusive, but instructive; his dim view of the prospects for leading a truly rewarding, worthwhile human life draws vivid attention to important questions about how and to what degree an atheistic world can nevertheless be conducive to human flourishing.