Before CopernicusIn 1984, Noel Swerdlow and Otto Neugebauer argued that Nicolaus Copernicus (14731543) explained planetary motion by using mathematical devices and astronomical models originally developed by Islamic astronomers in the thirteenth and fourteenth centuries. Was this a parallel development, or did Copernicus somehow learn of the work of his predecessors, and if so, how? And if Copernicus did use material from the Islamic world, how then should we