Voltaire's picaresque satire was intended as an attack upon the philosophical and religious orthodoxies of his time—in particular the Monadology of Gotthold Ephraim Lessing. This classic work of rationalist thought includes his theodicy: the argument that we are living in the best of all possible worlds because its foundation is the ultimate monad, a benevolent God.
In Candide, this optimistic credo is eagerly absorbed by the eponymous, naive picaro and his equally ingenuous beloved, Princess Cunegonde, from her long-winded tutor, Professor Pangloss.
In chapter 10, an old woman had suddenly appeared in the streets of Lisbon to save Candide and Cunegonde from the Grand Inquisitor. En route to Paraguay, Cunegonde despairs of finding a better life after the suffering she has endured and is chided by the old woman: "If you had suffered half what I have, there might be some reason for it." Cunegonde asks if the old woman has been raped by Bulgarians, seen her father and brother murdered, her mother cut to pieces, had both her castles demolished, and had watched her lover (Candide) tortured at an auto-da-fe, as she has?
In chapter 11, the old woman, who turns out to be the daughter of Pope Urban and the Princess of Palestrina, recounts a life packed with enough incidents of personal violation and bloodshed to dwarf even that of the extremely battered protagonists, including the sacrifice of one buttock to feed starving Janissaries. She continues:
I have grown old in misery and disgrace, living with only one buttock while remembering that I am the daughter of a Pope. I have been a hundred times upon the point of killing myself, but still I was fond of life. This ridiculous weakness is, perhaps, one of the dangerous principles implanted in our nature.
In short, my dear miss, I have a great deal of knowledge and experience in the world, therefore take my advice: divert yourself, and prevail upon each passenger to tell his story, and if there is one of them all that has not cursed his existence many times, and said to himself over and over again that he was the most wretched of mortals, I give you permission to throw me headfirst into the sea.
After Cunegonde humbly apologizes for her false assumption, Candide reflects:
It is a thousand pities that the wise Pangloss should have been hanged contrary to the custom of an auto-da-fe, for he would have given us a most admirable lecture on the moral and physical evil which overspreads the earth and sea; and I think I would have had courage enough to presume to offer (with all due respect) some few objections.
As Voltaire's satire suggests, the obedience induced by Leibniz's theodicy was an extremely useful tool to authorities of every stripe in encouraging the acceptance of outrages such the Inquisition along with more secular types of injustice. The philosophical notion that we live in the best of all possible worlds, he seems to say, is an idea which belies the human experience of suffering and the visceral, even biological will to survive despite its worst depredations.