The Zend-Avesta, or sacred books of the Pārsīs, is really a collection of various fragments. The first part, which may be called the Avesta proper, contains the Vendīdad, the Visparad and the Yasna. The Vendīdad is a compilation of religious lore and mythological tales, the Visparad is a collection of litanies for the sacrifice, while the Yasna, too, is composed of litanies, but it also contains five hymns or Gāthas written in a different dialect, which is older than the language of the greater part of the Avesta. These three books are found in manuscripts in two different forms. Sometimes either of them is found alone or accompanied by a Pahlavī translation, or the three are mingled together according to the requirements of the liturgy. The second portion of this work is generally known as the Khorda-Avesta, and is composed of short prayers, which are recited not only by the priests but by all the faithful, at certain moments of the day, month or year, and in the presence of the different elements. It is also customary to include in the Khorda or small Avesta, the Yaśts or hymns of praise to the several Izads or Yazatas. The sacredness of the Avesta is to a certain extent reflected upon a work called the Bundehesh, which was written in Pahlavī, or mediæval Persian, during the Sassanian age. According to the Pārsī traditions the bulk of Zoroastrian literature was formerly much greater than now. It is claimed that the Vendīdad is the only survivor of the twenty-one Nosks or books which formed the primitive Avesta revealed by Ormazd to Zoroaster, and also that the eighteen Yaśts were originally thirty in number, there having been one for each of the Izads who preside over the thirty days of the month. The classic authors agree with the Pārsīs in the statement that the early books of the Zend-Avesta were much more extensive than at present, the sacred literature of the Zoroastrians having suffered heavy losses in consequence of the ravages of the Persian empire by Greeks and Arabians. It appears from the third book of the Dīnkard that at the time of Alexander’s invasion there were only two complete copies of the sacred books, one of which was traced upon skins in golden letters and deposited in the royal archives at Persepolis, where it was burned by Alexander[147] while the other having been placed in another treasury fell into the hands of the Greeks, and was translated into their language. The Arḍā-Vīrāf-nāmak mentions only one copy of the Avesta, which was deposited in the archives at Persepolis and burned by Alexander; it also mentions the fact that he killed many of the priests and nobles. Both of these accounts were written, it is true, long after the events they describe, so they merely represent the tradition which had been handed down from one generation to the next, but as they were written before the Arabian conquest[148] they cannot have confounded the ravages of Alexander with those of the Mohammedans,