The phrase “We live in the best of all possible worlds” comes from the works of the German philosopher, mathematician, and polymath Gottfried Wilhelm Leibniz (1646-1716). This idea is a key component of Leibniz’s philosophical system, which aims to reconcile the existence of evil in the world with the idea of an all-powerful, all-knowing, and benevolent God. Leibniz’s optimism is grounded in his belief in a principle called the Principle of Sufficient Reason, which holds that there is a reason or explanation for everything that happens or exists. According to Leibniz, God created the world as a harmonious system, and because God is perfect, He must have chosen the best possible option among all the possible worlds He could have created. In this view, even though we might experience suffering and evil in our lives, these are all part of the greater plan and contribute to the overall goodness of the world. Leibniz believes that any other world would have been less perfect, less harmonious, and less good than the one we live in. His optimism has been criticized and satirized by other thinkers, most famously by Voltaire in his novel “Candide,” which portrays a naive protagonist who blindly follows the idea of living in the best possible world, only to be repeatedly disillusioned by the realities of life.