To gain a better understanding and appreciation for Candide, consider the following:
Philosophical Optimism – The belief that everything that happens in the world has some point and, in the end, everything happens for the best. (This phrase is spoken frequently in the book.) For example, in the event of a disaster, the “good end” of what seems to be a tragedy may not be apparent at the moment, but good will eventually come out of the disaster.
The Problem of Evil – The presence of evil in this world is something with which philosophers, theologians, and average people have long grappled. Philosophers pose this question: “If God is all good and all knowing, how can He allow such terrible, evil things to happen in a world that He has created?”
Divine Providence – Allied with the belief in Philosophical Optimism is a religious notion that there is a divine will that guides our fate; that is, everything that happens to us is God's will. Related to the question of Divine Providence is the question of Free Will. If our lives are ordained by God, are we responsible for choosing good or evil in our lives? Do we have any control over our lives, or are we simply pawns of fate?
Cause and Effect – This idea is used by religious philosophers to prove the existence of God. They argue that for every effect there must have been a cause; in tracing this back, eventually the answer they find is that the “first cause” is God.
Sufficient Reason – In Leibnitz's philosophy, the “sufficient reason” is that which justifies the existence of things. Like the first cause, the ultimate sufficient reason is God.