the notation is multiplicative-additive as opposed to the ciphered-additive standard system and requires knowing 12 letters, instead of 36, to write numbers less than 10,000. Numbers greater than that could be written using multiplicative combinations of just 2 or 3 signs, but using all 36 letters. Stephen Chrisomalis believes this system was created by Anania since it only occurs in his works and is not found in Greek, Syriac, Hebrew, or any other alphabetic numeral system. Allen Shaw has argued it was just a variant of the Armenian numerals designed specifically for the representation of large numbers. No other writer used it. Astronomical One of Anania's most significant works is the Cosmology (Տիեզերագիտութիւն, Tiezeragitut’iun). Abrahamian's version is composed of ten chapters, with an introduction titled "In the Fulfillment of a Promise", implying a patron. It covers the sun, the moon, celestial spheres, constellations, the Milky Way, and meteorological changes. Works used for the parts of the Cosmology include the Bible (mostly the Pentateuch and Psalms) and works by the Church Fathers. Anania cites the work of Basil of Caesarea, Gregory the Illuminator, and Amphiolocus (perhaps, of Iconium). Some chapters of the work, such as "On Clouds" (also called "On the Sky" or "Concerning the Skies"), are largely based on Basil's Hexameron. Anania also repeats the classical Greek notions in the fields of astronomy, physics or meteorology. Pambakian wrote about the significance of the Cosmology: Another of Anania's astronomical works, Tables of the Motions of the Moon (Խորանք ընթացիք լուսոյ, xorank‘ ĕnt'ac'ik' lusoy), is based on the works of Meton of Athens and his own observations. Perpetual calendar In 667 Anania was invited by Catholicos Anastas I of Akori (r. 661/2–667) to the Armenian Church's central seat at Dvin to establish a fixed calendar of the movable and immovable feasts of the Armenian Church. The result was a perpetual calendar based on a 532-year cycle (ՇԼԲ բոլորակ), combining the solar cycle and the lunar cycle since they coincide every 532 years. It was first proposed by Victorius of Aquitaine in 457 and adopted by the Church of Alexandria. Anania's calendar was never implemented by the Armenian Church; Hovhannes Draskhanakerttsi believes that Anastas's death prevented a church council from ratifying it. Geographical The Ashkharhatsuyts (classical Armenian: Աշխարհացոյց, Ašxarhac'oyts, lit. "showing the world") is an anonymously published world map, believed to have been written sometime between 610 and 636. According to Elizabeth Redgate,