INTRODUCTION
Scope of the work. This book is the revised and much enlarged edition of my Zoroastrian Theology, which has been out of print for the past fifteen years. The publication of my Zoroastrian Civilization and Our Perfecting World, Zarathushtra's Way of Life, and professional duties have delayed the completion of the work. I have inserted new material in several chapters and added nineteen new chapters to the book. I have given a concise account of the religious beliefs and practices prevalent among the Zoroastrians and their early Iranian ancestors from the pre-Gathic times to the present day and named the book History of Zoroastrianism.
Arrangement and method. I have divided the entire period of the history of Zoroastrianism on the linguistic basis. The earliest Zoroastrian documents are the Gathas, written in the Gathic dialect. They represent the earliest phase of the religion of Zoroaster. But ancient Iran had a religion which preceded Zoroastrianism in point of time. I have labelled this period pre-Gathic; for its beginning is lost in remote antiquity, and the advent of Zoroaster brings its end.
The time when Zoroaster flourished is a moot question. The approximate date at which he lived is 1000 b.c. Zoroaster revolutionizes the religious life of the Iranians, which hitherto represented the evolutionary phase of religion. It was the movement in which we find the religious thought creeping for ages to rise from the lower to the higher level. To put this in another way, the pre-Gathic religion of Iran is the evolution of the religious thought of many men and many ages; Zoroaster's is the creation of one man and one age. The prophet of Iran establishes a new religion. In the pre-Gathic religion the trend of religious thought struggles from the complex to the simple, from concrete to abstract, and is yet the farthest removed from the ideal stage. Zoroastrianism, on the other hand, as preached in the Gathas is the very embodiment of the simple and the abstract. It is the realiza-
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