Between Copernicus and Galileo is the story of Christoph Clavius, the Jesuit astronomer and teacher whose work helped set the standards by which Galileo's famous claims appeared so radical, and whose teachings guided the intellectual and scientific agenda of the Church in the central years of the Scientific Revolution. Though relatively unknown today, Clavius was enormously influential throughout Europe in the late 16th and early 17th centuries through his astronomy books - the standard texts used in many colleges and universities, and the tools with which Descartes, Gassendi and Mersenne, among many others, learned their astronomy. James Lattis uses Clavius's own publications, as well as archival materials, to trace the central role Clavius played in integrating traditional Ptolemaic astronomy and Aristotelian natural philosophy into an orthodox cosmology. Although Clavius strongly resisted the new cosmologies of Copernicus and Tycho, Galileo's invention of the telescope ultimately eroded the Ptolemaic world view. By tracing Clavius's views from medieval cosmology to the 17th century, Lattis illuminates the conceptual shift from Ptolemaic to Copernican astronomy and the social, intellectual and theological impact of the Scientific Revolution.