Sinai developed a new homiletic genre whose verses in the complex ode meter were composed over a melodic model: the heirmos. During the 7th century kanons at the Patriarchate of Jerusalem still consisted of the two or three odes throughout the year cycle, and often combined different echoi. The form common today of nine or eight odes was introduced by composers within the school of Andrew of Crete at Mar Saba. The nine odes of the kanon were dissimilar by their metrum. Consequently, an entire heirmos comprises nine independent melodies (eight, because the second ode was often omitted outside Lenten period), which are united musically by the same echos and its melos, and sometimes even textually by references to the general theme of the liturgical occasion—especially in acrosticha composed over a given heirmos, but dedicated to a particular day of the menaion. Until the 11th century, the common book of hymns was the tropologion and it had no other musical notation than a modal signature and combined different hymn genres like troparion, sticheron, and canon. The earliest tropologion was already composed by Severus of Antioch, Paul of Edessa and Ioannes Psaltes at the Patriarchate of Antioch between 512 and 518. Their tropologion has only survived in Syriac translation and revised by Jacob of Edessa. The tropologion was continued by Sophronius, Patriarch of Jerusalem, but especially by Andrew of Crete's contemporary Germanus I, Patriarch of Constantinople who represented as a gifted hymnographer not only an own school, but he became also very eager to realise the purpose of this reform since 705, although its authority was questioned by iconoclast antagonists and only established in 787. After the octoechos reform of the Quinisext Council in 692, monks at Mar Saba continued the hymn project under Andrew's instruction, especially by his most gifted followers John of Damascus and Cosmas of Jerusalem. These various layers of the Hagiopolitan tropologion since the 5th century have mainly survived in a Georgian type of tropologion called "Iadgari" whose oldest copies can be dated back to the 9th century. Today the second ode is usually omitted (while the great kanon attributed to John of Damascus includes it), but medieval heirmologia rather testify the custom, that the extremely strict spirit of Moses' last prayer was especially recited during Lenten tide, when the number of odes was limited to three odes (triodion), especially patriarch Germanus I contributed with many own