In 1543, the Polish astronomer Nicolaus Copernicus lay on his deathbed, reportedly holding his just-published masterpiece, The Revolutions of the Heavenly Spheres , in his hands. Placing the sun at the center of the universe, Copernicus launched modern science, leading to a completely new understanding of the universe, and humanity's place within it. But what did Copernicus really believe? Some argue that he anticipated the vast secularizing impact his ideas would have on history. Others contend that Copernicus was a man of his time and, on the whole, accepted its worldview. William T. Vollmann navigates this territory with the energetic prose and powerful intelligence for which