Candide is characterised by its sarcastic tone, as well as by its erratic, fantastical and fast-moving plot. A picaresque novel with a story similar to that of a more serious bildungsroman, it parodies many adventure and romance clichés, the struggles of which are caricatured in a tone that is mordantly matter-of-fact. Still, the events discussed are often based on historical happenings, such as the Seven Years' War and the 1755 Lisbon earthquake. As philosophers of Voltaire's day contended with the problem of evil, so too does Candide in this short novel, albeit more directly and humorously. Voltaire ridicules religion, theologians, governments, armies, philosophies, and philosophers through allegory; most conspicuously, he assaults Leibniz and his optimism.