At the end of the ninth century John the Deacon (d. c. 882) ascribed to Gregory I the compilation of the books of music used by the schola cantorum established at Rome, by that pope.
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Manegold's book also contained an account of the life of Gregory VII, reflecting the Vita by John the Deacon of Gregory the Great; this shares details with chronicles of Berthold of Reichenau and Bernold of St Blasien, writing in the part of southern Germany in which Manegold had sheltered after having to leave Alsace.