In the eighteenth century an ancient Iranian document was discovered. It is called the Avesta. It is the ancient and authoritative record of the Iranian religion. It constitutes the basis on which the whole fabric of Iranian religion and philosophy has been created. The Avesta claimed to be the work of Zoroaster himself, the prophet of the Zoroastrian religion. This text leads scholars to read the national character with much more distinctness and truth than in the descriptions of foreigners, which had been known in the past. The Avesta was independent of any external influences upon Persian civilization. The author’s goal is to trace out the history of the introduction to modern knowledge of the writings of the Avesta and of the study and labor which has since been expended upon them. Modern knowledge of Zoroastrianism is lacking because the religion is all but dead, practiced by a few thousand Parsis, who do not hold a proper understanding of the doctrines they hold dearly.