Rabanus Maurus Magnentius (c. 780 – 4 February 856), also known as Hrabanus or Rhabanus, was a Frankish Benedictine monk, the archbishop of Mainz in Germany and a theologian. He was the author of the encyclopaedia De rerum naturis (On the Nature of Things). He also wrote treatises on education and grammar and commentaries on the Bible. He was one of the most prominent teachers and writers of the Carolingian age, and was called "Praeceptor Germaniae," or "the teacher of Germany." On the Roman calendar (Martyrologium Romanum, 2001, pp. 126f.), he is celebrated on 4 February and listed as 'sanctus,' though the online version of the Catholic Encyclopedia of nearly a century earlier lists him as 'beatus.'