Avesta as "Fragments Tahmuras"; and the "Hadokht Nask" "volume of the scriptures" with two fragments of eschatological significance. Only texts preserved in the Avestan language count as scripture and are part of the Avesta. Several other secondary works are nonetheless crucial to Zoroastrian theology and scholarship. The most notable among the Middle Persian texts are the "Dēnkard" ("Acts of Religion"), dating from the ninth century; the "Bundahishn" ("Primordial Creation"), finished in the eleventh or twelfth century, but containing older material; the "Mainog-i-Khirad" ("Spirit of Wisdom"), a religious conference on questions of faith; and the "Book of Arda Viraf", which is especially
Avesta collection now lies in the Royal Library, Denmark ('K'-series). Other large Avestan language manuscript collections are those of the British Museum ('L'-series), the K. R. Cama Oriental Library in Mumbai, the Meherji Rana library in Navsari, and at various university and national libraries in Europe. In its present form, the Avesta is a compilation from various sources, and its different parts date from different periods and vary widely in character. Only texts in the Avestan language are considered part of the Avesta. According to the "Denkard", the 21 "nask"s (books) mirror the structure of the 21-word-long "Ahuna Vairya" prayer: each