Zoroastrianism, or more natively Mazdayasna, is one of the world's oldest religions, "combining a cosmogonic dualism and eschatological monotheism in a manner unique... among the major religions of the world." Ascribed to the teachings of the Iranian Prophet Zoroaster (or Zarathustra), he exalted their deity of wisdom, Ahura Mazda, (Wise Lord) as its Supreme Being. Leading characteristics, such as messianism, heaven and hell, and free will are said to have influenced other religious systems, including Second Temple Judaism, Gnosticism, Christianity, and Islam. With possible roots dating back to the second millennium BCE, Zoroastrianism enters recorded history in the 5th-century BCE, and including a Mithraic Median prototype and Zurvanist Sassanid successor it served as the state religion of the pre-Islamic Iranian empires from around 600 BCE to 650 CE. Zoroastrianism has no major theological divisions, though it is not uniform; modern-era influences having a significant impact on individual and local beliefs, practices, values and vocabulary, sometimes merging with tradition and in other cases displacing it. In Zoroastrianism, the purpose in life is to "be among those who renew the world...to make the world progress towards perfection." Its basic maxims include: Humata, Hukhta, Huvarshta, which mean: Good Thoughts, Good Words, Good Deeds. There is only one path and that is the path of Truth. Do the right thing because it is the right thing to do, and then all beneficial rewards will come to you also. The most important texts of the religion are those of the Avesta, which includes the writings of Zoroaster known as the Gathas, presented here in this book which are enigmatic poems that define the religion's precepts, and the Yasna, the scripture. The full name by which Zoroaster addressed the deity is: Ahura, The Lord Creator, and Mazda, Supremely Wise. He proclaimed that there is only one God, the singularly creative and sustaining force of the Universe. He also stated that human beings are given a right of choice, and because of cause and effect are also responsible for the consequences of their choices. Zoroaster's teachings focused on responsibility, and did not introduce a devil, per se. The contesting force to Ahura Mazda was called Angra Mainyu, or angry spirit. Post-Zoroastrian scripture introduced the concept of Ahriman, the Devil, which was effectively a personification of Angra Mainyu. Included in this interpretation of the book is a list of Glossary terms for the reader to further understand one of the oldest religions in the world.

The manuscript S1 is one of the chief witnesses to the Sanskrit Yasna, containing the Avestan text of the Zoroastrian Yasna liturgy to chapter 46.19, together with a Sanskrit translation and commentary. This book contains the complete, full-colour set of facsimile images of S1. An introduction by Leon Goldman provides an overview of the Zoroastrian Sanskrit tradition together with a discussion of the S1 manuscript covering its physical appearance, its age and history, and for the first time, a detailed palaeographic analysis of the Avestan and Sanskrit text.

The oldest Zoroastrian religious scripture, handed down from ancient times, is the Avesta. One section of the holy book is known as the "Khordeh Avesta" or "Smaller (i.e. Selected) Avesta." This is the book of daily prayers of the Zoroastrians, including the most sacred prayers or manthras, as well as graces said over meals and other occasions, blessings, and hymns to spiritual beings. It is a cherished possession of every devout Zoroastrian household. Zoroastrians recite their prayers in a sacred language known as Avestan. The celebrated Avesta scholar and priest (Ervad) Kavasji Edulji Kanga prepared an edition of this prayer book in 1880 A.D., with Gujarati translation. An English edition was first printed in 1993, which has become very scarce. Due to the popularity of Kanga's editions, and the accuracy of its pronunciation, this new printed edition was prepared, correcting the frequent printer's errors found in the 1993 edition.

Zoroastrianism is one of the world's oldest religions, though it is not among the best understood. Originating with Iranian tribes living in Central Asia in the second millennium BCE, Zoroastrianism was the official religion of the Iranian empires until Islam superseded it in the seventh century AD. Centered on the worship of Ahura Mazda, the All-knowing Ruler, Zoroastrianism follows the practices and rituals set out by the prophet Zarathustra, according to the indigenous tradition. As one of the world's great religions, Zoroastrianism has a heritage rich in texts and cultic practices. The texts are often markedly difficult to translate, but in this volume, Prods Oktor Skjærvø, professor of ancient Iranian languages and culture at Harvard, provides modern and accurate translations of Zoroastrian texts that have been selected to provide an overview of Zoroastrian beliefs and practices. In a comprehensive introduction to these sacred texts, Skjærvø outlines the history and essence of Zoroastrianism and discusses the major themes of this the first fully representative selection of Zoroastrian texts to be made available in English for over a century.