 John lived in the second half of the 12th century, and served as a deacon and canon of the Basilica of St. John Lateran.He compiled a work on this papal basilica, and dedicated it, in the preface, to Pope Alexander III (c. 1100/1105 – 1181), thereby indicating the date of its composition.It was obviously a secondary object of the author in composing this work to support the canons of the Lateran in their dispute for precedence with the canons of St. Peter's Basilica.