The Augustinian friar Johannes de Sacro Bosco, or Sacro Busto, (c.1200-c.1256) was an astronomer and mathematician who may have hailed from England or Ireland. He taught mathematics at the University of Paris. His Sphaera Mundi, which was written in c.1230, is his main work and treats the subject of spherical astronomy of the Ptolemaic system. It became one of the most popular scientific works in the Middle Ages. Included in this volume is Theorica Planetarum by Gerardus Cremonensis.
