 Israel 's poem De arte metrica was dedicated to Rotbert , Archbishop of Trier . It was almost certainly composed in England , and the dedication was probably a successful plea for Rotbert 's patronage when Æthelstan died in 939 . From about 940 Israel was the tutor of Bruno , the future Archbishop of Cologne and brother of the Holy Roman Emperor , Otto the Great . <unk> of Tegernsee described Israel as Rotbert 's " shining light " . In 947 Israel attended a synod at Verdun presided over by Rotbert , where he was referred to as a bishop , but without identification of his see . He was famous as a schoolmaster and probably played an important role in Emperor Otto 's establishment of a court school at Aachen . 
