No attempt here is made to present in detail an account of the philosophy of Gottfried Wilhelm Leibnitz (1646-1716), which Voltaire called "optimism," the term he used as the subtitle to Candide, but only to call attention to the points relevant to an understanding of the philosophical tale. Pangloss referred to the German as "the most profound metaphysician of Germany," and, in view of his constant use of Leibnitzian terms and concepts, he has often been identified with the German philosopher. To that extent, through the character of Pangloss, Voltaire satirized Leibnitz. But the great philosopher and mathematician, the man who was co-discoverer with Newton, yet independently, of differential calculus, was anything but such a ridiculous figure.
Although as early as 1733, Voltaire had written in a note in Temple du goût that no man of letters had done Germany greater honor and that Leibnitz was more universal than his revered Newton. It was not until 1737 that he really became interested in the philosophy. In that year Frederick the Great wrote to him enthusiastically about the works of Christian Wolff, the man credited with systematizing Leibnitz's views. His mistress, Mme. du Châtelet, was a dedicated Leibnitzian, and during his stay at Cirey, Voltaire, although concentrating largely on Newton, took part in the study and lengthy discussions of the German's philosophy.
Early and as late as 1756, Voltaire had praise for Leibnitz. Thus in the letter to Koenig, the German mathematician, dated November 1752, he expressed admiration for the philosopher's manner of thinking and his tendency to scatter the "seeds of ideas." And in the Siècle de Louis XIV (1756), he wrote approvingly of the man. But fundamentally Voltaire was suspicious of all attempts at systematic philosophy. In 1737, he wrote to Frederick the Great: "All metaphysics contain two things: all that intelligent men know; second, that which they will never know." Certain views he did share with Leibnitz. He too believed in a Supreme Being who created the universe and whose glory is manifest in the Heavens and on the earth; and he rejected the idea that the world was entirely mechanical or determined or material. The record shows that he did not reject optimism without a struggle. Among his works that indicate a tendency to hold on to an optimistic view of life are Mondain (1736), Discourse en vers sur l'homme (1736-41), Micromégas (1739), Le monde comme il va (1746), and Zadig (1747). But it was indeed a struggle for him. For example, the idea that human events can be explained by providentialism he could not accept. Deist as he was, his God was an absentee one, to use Carlyle's phrase. In a letter written in the late 1730s, he used the analogy of the mice in the ship's hold and the complete indifference of the ship's master — the very same analogy he repeated near the end of Candide. By 1741, Voltaire had spoken out clearly against the major tenets of Leibnitzianism. He wrote: "Frankly, Leibnitz has only confused the sciences. His sufficient reason, his continuity, his plenum (all-embracing whole of the universe), his monads, are the germs of confusion of which M. Wolff has methodically hatched fifteen volumes in quarto which will put the German heads more than ever in the habit of reading much and understanding little." Although he had some praise for Leibnitz in the Siècle de Louis XIV (1756), he also called him "un peu charlatan."
The two main points of Leibnitzian philosophy are that God is beneficent and that, in creating the world, He created the best possible one. It should be realized that the philosopher did not argue that the world was perfect or that evil was non-existent. What he did mean was that, thanks to God's goodness and His constant concern with his creation, that which is moral and right finally emerges: it is the ultimate reality. It is all a matter of being able to see the Divine plan in its entirety and not to judge by isolated parts. Leibnitz held that nature moves in an orderly way; that its laws are immutable; that any deviation would upset the universe. Matter he defined as an indivisible something. His name for it was monad. All matter, according to his theory, was composed of monads, and these rise on a hierarchical scale from the lowest to the highest. And thus he accounts for the principle of continuity and being in the Great Chain of Being.
By the time he came to write Candide, Voltaire's wide reading and experiences provided him with sufficient reason for rejecting these ideas. The phrase "all is well," a refrain in Candide, voiced again and again by the young hero and Pangloss, his teacher, is scorned; "the best of all possible worlds" becomes a grim joke. The belief that everything forms a chain and that each individual must keep his place in that chain is dismissed as sheer nonsense. Voltaire also rejects the belief that personal evil only contributes to the general good, that human events are wholly in terms of providentialism, and that harmony is pre-established.