Petrus Alfonsi was an important and unusual figure in the "twelfth-century renaissance" whose interests embraced polemical theology, astronomy, and literature, each an area in which he  made important contributions to the development of medieval thought.  Perhaps this diversity of interests is what has robbed Alfonsi of his due in modern scholarship, for he has fallen through the cracks, between various academic disciplines; he has received less acclaim among modern medievalists than he had among medieval writers.  In this first book-length treatment of Alfonsi, Tolan  presents a thorough introduction to Alfonsi's thought and its importance to the Middle Ages.