Some 15 billion years ago, a titanic explosion created space and time and started the universe on its epic journey towards ever greater complexity. Out of a tiny primordial speck was woven an immense tapestry of hundreds of billions of galaxies, each home to as many stars. In one of those galaxies, on a planet circling a nondescript star, there emerged human beings with the ability to marvel at the beauty and harmony of the cosmos. In clear, simple language, this account explains the Big Bang and its ever-expanding consequences.