| 1. Yasna (including Gathas) | 4. Minor Texts |
| 2. Visperad | 5. Vendidad |
| 3. Yashts | 6. Fragments. |
No single existing manuscript contains all these complete; but the Yasna, Visperad, and Vendidad are usually found grouped together as a sort of prayer book, and are called Vendidad Sadah or 'Vendidad pure,' i. e. text without commentary; because when they are thus grouped for liturgical purposes the Avesta text is not accompanied by the rendering and comments in the Pahlavi language.
Tradition claims that the original Zoroastrian Avesta was in itself a literature of vast dimensions. The Latin writer, Pliny, in his Natural History, speaks of 2,000,000 verses of Zoroaster. Semitic authors add testimony about the works of the prophet being translated into seven or even twelve different tongues. A statement may also be quoted to the effect that the original Avesta was written on 1,200 parchments, with gold illuminated letters, and deposited in the library at Persepolis. It was this copy that Alexander the Great — 'the accursed Iskander,' as Parsi tradition calls him — allowed to be destroyed, when at the request of Thais, as the story goes, he permitted the burning of the palace. It is also implied that there was another copy of the original Avesta which somehow perished at the hands of the Greeks. More blame, doubtless, than is just, is put upon Alexander; but his shoulders are broad enough to bear the burden; and his invasion, it is true, was ultimately the cause of much of the scriptures being forgotten, or falling into disuse, in consequence of the ruin he brought upon the religion. The tradition, at all events, that the original Avesta consisted of twenty-one 'Nasks' or books, rests, it seems, on good foundation. There is no special reason to doubt it.
The Sassanian rulers (A.D. 229-379), who gathered and codified all they could collect of the texts, were able to give a detailed outline of the contents and extent of each of these Nasks. From their description the original Avesta must have been a sort of encyclopædia, not alone of religion, but of many matters relating to the arts, sciences, and professions, closely
