Hume's 1779 book on the existence of God remains vastly influential. Using the conceit of a cleverly crafted fictional conversation, Dialogues argues on the one hand that a universe that looks designed must have a designer—and that if it has as 'an uncaused first cause,' that cause can only be God. But, on the other hand, if there is evil in the world, then there cannot be a God. Hume weaves the overarching question of whether we can truly know God's nature into the entire debate. Dialogues makes an elegant case for empiricism, the theory that knowledge must be built on what we experience through our senses.