يوحنا الدمشقي
The common schedule and the focus on the circle around John of Damascus is confirmed by a ninth-century treatise called "Hagiopolites" (from "hagios polis", "Holy City", referring to Jerusalem) which only survived in a complete form as a late copy. The Hagiopolites treatise served presumably as an introduction of a book called "tropologion" – a 9th-century chant book which had been replaced soon by the book octoechos, as part of the sticherarion one of the first chant books fully provided with musical notation. The Hagiopolitan emphasis on John of Damascus was obviously the late result of a 9th-century redaction around the Second Council of Nicaea in 787, so it was part of the later Studites reform between Jerusalem and Constantinople and it was motivated theologically, not only because of his contributions to the tropologion, but also because of the keyrole which John of Damascus' polemic against the iconoclasts had during this council.