Leibnitz emphasized, in his Discours de Metaphysique (Discourse on Metaphysics) (1686) the role of a benevolent creator. He called the constituent components of the universe monads, and while the philosophy of monads is of little concern to readers of Candide, the conclusion which Leibnitz drew from these monads is crucial to an understanding of optimism.
             Leibnitz argued that all of these monads were linked in a complex chain of cause and effect and that this linking had been done by a divine creator as he created the harmonious universe. Since he was benevolent, omnipotent, and omniscient, he logically would create the best of all possible worlds. Hence, everything that happens in the universe is part of this greater plan, and thus must be for the best. Humans cannot appreciate how the evils encountered in every day life contribute to the best of universes and universal harmony, but they do, nonetheless.
             Optimism was attractive to many because it answered a profound philosophical question that mankind had been grappling with since the beginning of faith: if God is omnipotent and benevolent, then why is there so much evil in the world? Optimism provides an easy way out of this philosophical dilemma: God has made everything for the best, and even though one might experience personal misfortune, God (via your misfortune) is still helping the greater good.
             Voltaire's experiences led him to dismiss the idea that this is the best of all possible worlds. Examining the death and destruction, both man-made and natural (including the Lisbon earthquake) Voltaire concluded that everything was not for the best. Bad things do happen, and they happen without being part of a greater good.
             How, then, did Voltaire answer the question so easily solved by optimism, namely, why does evil exist in the world? As a Deist, Voltaire's God was one who initially created the world, and then left it to its own devices. When, at the end of Candide, Pangloss...