Polydore Vergil (c.1470–1555) was a controversial critic of the church of his day. As this essay will show, his radical solution to its problems was based upon his reading of the church’s history. An Italian cleric on English soil for much of his life, Vergil is most famous for his Anglica Historia (1533), the first Tudor history of England. However, he was also responsible for another great (although now neglected) work, De Inventoribus Rerum (‘on the inventors, or discoverers, of all things’). Consisting of eight volumes, it is an example of early encyclopaedic technique from original Latin and Greek sources, including the Bible, Josephus and Eusebius, as well as observation from contemporary life, in which ‘invention’ is depicted as a category of historiography and a means of examining scientific and cultural history. The first three books were published in 1499 in Venice and deal mainly with scientific phenomena. The other five books, with which we are concerned here, consider the origins of Christian institutions (initia institutorum rei Christianae) and were published much later, in 1521, although Vergil continuously revised the entire De Inventoribus Rerum until his death. The topics covered range from early church history, baptism, clerical and religious orders, penance, prayers and simony, to heresies and schisms, martyrs and the triumph of Christianity. An extremely popular work, with over forty editions in Vergil’s lifetime, it was, nonetheless, censured for its criticisms of the church. Indeed, the purpose of Books IV–VIII was to demonstrate what was initiated by Christ and what the true nature of the church was, not by examining its doctrine but by seeking the origins of its practice.