The student of religions has few options when it comes to Zoroastrianism. Its scriptures have not been translated into English in over a century and there are vanishingly few scholars capable of dealing with the extreme philological and historical challenges of understanding and translating the material. Thank heavens that of the few books we have, Boyce's book is among them. Flawed though it may be, it is an invaluable overview of the history of Zoroastrianism from the time of its founder to the present day.
Boyce did possess ample expertise to motivate and present the history and doctrines of Zoroastrianism in plentiful detail. Too plentiful, in fact, for the tastes of this reader, and I have a large appetite for dry academic material. Even so, plowing through this relentless presentation of technical terms, unfamiliar names, and obscure dynasties and languages was a daunting challenge, even at a short 200 pages.
For all Boyce's lavish attention to detail she presents a surprisingly one-sided picture of Zoroastrianism. You would never know reading this book that the historicity of Zarathustra has been challenged repeatedly, or that opinions are sharply divided on whether or not Darius and his successors were Zoroastrians.
Boyce has arrived at her conclusions and that is what you get. Her commitment to this interpretation goes too far at times and compromises her scholarly objectivity, as when she refers to the Zurvanites as betrayers of Zarathustra's doctrine and a "deep and grievous heresy". Such ideas simply do not have a place in academic scholarship.
If we are to have too few books on Zoroastrianism in English, I am glad this one errs on the side of too much detail and minutiae. This book is the account of a scholar with very deep knowledge indeed, and I am glad for it, flaws and all.