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The study of Avestan and Middle Persian texts is the philological and historical discipline devoted to the surviving literature of pre-Islamic Iran, written in its two principal literary languages. Avestan is the language of the sacred corpus of Zoroastrianism, the Avesta, composed over many centuries and transmitted orally before being committed to writing. Middle Persian (also called Pahlavi) is the language of the Zoroastrian community of the Sasanian and early Islamic periods, whose extensive theological, legal, and narrative literature forms the second great body of texts. The subfield concerns itself with editing, translating, and interpreting these works, and with reconstructing the religious, social, and intellectual worlds they reflect.
The Avesta is not a single book but a collection of liturgical and devotional compositions of different ages and genres. Its oldest layer, the Gathas, consists of seventeen hymns attributed to the prophet Zarathustra (Zoroaster), composed in an archaic dialect of Avestan known as Old Avestan. The remainder of the corpus—including the Yasna (the central liturgy), the Yashts (hymns to individual deities), the Videvdad (a legal-ritual text concerned with purity and pollution), and various shorter prayers and fragments—is written in Younger Avestan, a later and grammatically simpler form of the language. The Avestan texts are preserved in manuscripts copied long after their composition, and the oldest surviving codices date only to the thirteenth and fourteenth centuries CE. The pronunciation of Avestan was transmitted through a separate oral tradition, and the written form uses a script invented for the purpose during the Sasanian period (224–651 CE), which included letters to represent sounds not found in the Middle Persian alphabet.
Middle Persian literature is far more diverse in genre. It includes theological treatises and catechisms, such as the Denkard (an encyclopedic compendium of Zoroastrian knowledge) and the Bundahishn (a cosmological and eschatological work); legal texts; ritual instructions; wisdom literature and moral maxims; narrative and legendary material, including the Karnamag i Ardashir (the deeds of the first Sasanian king); and polemical and apologetic works composed in response to Islam, Christianity, and Manichaeism. These texts were written in the Pahlavi script, an abjad derived from Aramaic that preserves Aramaic spellings (called uzvarishn or Huzvarishn) for many common words while reading them as their Iranian equivalents—a feature that makes the texts challenging to read and edit. The Middle Persian corpus was produced and copied largely in the ninth and tenth centuries CE, though it incorporates older material and reflects Sasanian-era learning.
The two corpora are intimately connected. The Middle Persian texts frequently quote, paraphrase, and comment upon the Avesta, and they preserve much Zoroastrian exegesis (zand) that is otherwise lost. The relationship is not one of simple continuity, however: the Avestan texts are ritual and liturgical in character, while the Middle Persian literature is predominantly scholastic and didactic. Understanding how the later tradition interpreted, systematized, and sometimes transformed the older material is one of the central tasks of the field.
The subfield is driven by several enduring questions. The first concerns dating and authorship. The Gathas are among the oldest attested Iranian texts, but their precise date is disputed, with estimates ranging from roughly 1200 to 600 BCE. Because the texts themselves contain no explicit historical references, scholars must rely on linguistic archaism, comparative Indo-Iranian evidence, and indirect cultural clues. The dating of the Younger Avestan texts is even more uncertain, and the relative chronology of different sections of the corpus remains a matter of ongoing debate.
A second central question is the reconstruction of the original text. Neither the Avestan nor the Middle Persian corpus survives in a pristine form. The Avestan manuscripts are late and often corrupt, and the oral tradition that preceded them introduced both deliberate and accidental changes. The Middle Persian texts, for their part, survive in manuscripts that are frequently incomplete, and the Pahlavi script's ambiguities—many letters are homographs—make editorial decisions difficult. Textual criticism in this field is therefore not a mechanical exercise but a hermeneutical one, requiring judgments about grammar, style, and religious content.
A third question concerns the relationship between text and ritual. The Avesta is not a book of abstract theology but a collection of texts meant to be recited in the course of priestly ceremonies. Understanding the liturgical context of a given text is essential to interpreting it. The Middle Persian literature, by contrast, is largely the product of a learned elite reflecting on and systematizing that ritual tradition, often in response to external challenges. The field thus asks how religious practice, textual transmission, and intellectual reflection interacted across more than a millennium.
The stakes of these questions extend beyond philology. Zoroastrianism is one of the oldest living religions, and its texts are the primary evidence for its early history. The field also bears on the broader study of Indo-Iranian religion, on the history of the ancient Near East, and on the cultural memory of Iran. Because the texts are fragmentary and difficult, interpretations have varied widely, and the field has been marked by sharp disagreements over method and conclusion.
The modern study of these texts began in the eighteenth century, when European scholars first encountered Zoroastrian manuscripts brought from India, where the Zoroastrian community (the Parsis) had preserved them. The French scholar Abraham Hyacinthe Anquetil-Duperron published a translation of the Avesta in 1771, based on his study with Parsi priests, but his work was met with skepticism by some contemporaries who doubted the antiquity of the texts. The subsequent century saw the gradual establishment of Avestan philology on a sound footing, largely through the work of German and other European linguists who recognized the language's close kinship with Sanskrit and used comparative grammar to analyze it.
The late nineteenth and early twentieth centuries were the formative period of the discipline. The Danish scholar Niels Ludvig Westergaard and the German scholar Karl Friedrich Geldner produced critical editions of the Avestan texts, establishing the manuscript basis for all later study. The French scholar James Darmesteter translated the Avesta into French and wrote influential studies of its mythology and ritual. The most important figure of this period, however, was the German scholar Christian Bartholomae, whose Altiranisches Wörterbuch (Old Iranian Dictionary, 1904) remains a fundamental reference work. Bartholomae's grammatical and lexical work, together with his edition of the Gathas, set the standard for the field.
The study of Middle Persian texts developed along a parallel but distinct path. The Pahlavi literature was known to European scholars from the eighteenth century, but its difficult script and complex language slowed progress. The breakthrough came with the recognition of the Aramaic heterograms—the Aramaic spellings read as Iranian words—which allowed scholars to understand the texts' actual pronunciation and grammar. The French scholar Édouard Blochet and the British scholar Edward William West made early contributions, but the field was transformed by the work of the Danish scholar Kaj Barr and, above all, by the German scholar Henning (Walter Bruno Henning), whose studies of Middle Persian and other Middle Iranian languages in the mid-twentieth century established the modern understanding of the language's grammar and vocabulary. Henning's work was complemented by that of the British scholar Mary Boyce, who combined philological rigor with a deep interest in the living Zoroastrian tradition and its oral transmission.
The field has been organized less by rival schools than by a set of overlapping approaches that have succeeded and coexisted with one another. The oldest and most fundamental is the comparative-historical method, which treats Avestan as an Indo-Iranian language and uses Sanskrit, Old Persian, and other related languages to illuminate its grammar and lexicon. This approach, associated with Bartholomae and his successors, remains the indispensable foundation of all textual work. Its limitation is that it can say little about the religious content of the texts beyond what is linguistically recoverable.
A second approach, associated with the so-called "mythological school" of the late nineteenth and early twentieth centuries, sought to interpret the Avestan deities and narratives as reflexes of Indo-European or Indo-Iranian mythology. The most famous practitioner was the French scholar Georges Dumézil, whose tripartite theory of Indo-European society (priests, warriors, and herders/farmers) was applied to the Avesta and to the legendary history of Iran. This approach produced many suggestive parallels but has been criticized for imposing a rigid schema on texts that do not always fit it, and its influence has waned.
A third approach, which emerged in the mid-twentieth century and has become dominant, is the ritual and liturgical study of the Avesta. This approach, associated with Mary Boyce and, more recently, with the Finnish scholar Jaakko Hämäläinen and others, emphasizes that the Avestan texts are not a random collection of myths and doctrines but a structured liturgical corpus whose arrangement reflects the actual performance of Zoroastrian ritual. Scholars working in this vein have reconstructed the sequence of the Yasna ceremony, analyzed the use of the Yashts in the calendar of feasts, and shown how the Videvdad is organized around the practical concerns of priestly purity. This approach has the great advantage of grounding interpretation in the texts' own context, but it can be difficult to apply to the older and more archaic layers, whose original ritual setting is no longer recoverable.
A fourth approach is the historical and social-historical study of the texts, which asks what the Avestan and Middle Persian corpora can tell us about the societies that produced them. This approach has been particularly fruitful for the Middle Persian literature, which contains explicit references to historical events, institutions, and controversies. Scholars such as the Iranian historian Touraj Daryaee and the German scholar Josef Wiesehöfer have used the Pahlavi texts to illuminate Sasanian administration, law, and religious policy. For the Avestan texts, the historical approach is more speculative, since the texts are largely devoid of historical reference, but attempts have been made to date the Younger Avestan layers by reference to the geographical and political world they presuppose.
A fifth approach, which has grown in importance since the late twentieth century, is the study of the texts as literature and as products of a long tradition of interpretation. This approach attends to the rhetorical strategies, generic conventions, and intertextual relationships of the texts, and it treats the Middle Persian zand (commentary) not as a transparent window onto the Avesta but as a creative reinterpretation that shaped later Zoroastrianism. Scholars working in this vein have shown how the Pahlavi texts selectively quote, expand, and sometimes correct the Avestan material, and how the tradition of commentary itself became a site of theological innovation.
These approaches are not mutually exclusive, and most scholars combine them. The comparative-historical method provides the linguistic foundation; the ritual approach supplies the interpretive context; the historical approach situates the texts in their social world; and the literary approach attends to their formal and rhetorical dimensions. The field is nonetheless marked by genuine disagreements, particularly over the dating of the Avestan texts and over the degree of continuity between the Avestan and Middle Persian traditions. Some scholars emphasize the rupture between the two corpora, arguing that the Middle Persian literature represents a fundamentally different, scholastic form of Zoroastrianism; others stress the continuity of priestly tradition and ritual practice.
The contemporary field is small but active, with centers of study in Europe, North America, and Iran. The most important ongoing project is the Encyclopaedia Iranica, a comprehensive reference work that covers all aspects of Iranian civilization and includes numerous articles on Avestan and Middle Persian texts. The field also benefits from the work of the Corpus Inscriptionum Iranicarum, which publishes editions of the Middle Persian inscriptions, and from the ongoing production of critical editions and translations of individual texts.
Digital humanities have begun to transform the field. The Avestan Digital Archive, based at the University of Tehran, has made high-resolution images of Avestan manuscripts available online, and the TITUS project (Thesaurus Indogermanischer Text- und Sprachmaterialien) at the University of Frankfurt hosts digitized versions of many Avestan and Middle Persian texts. These resources have made it possible for scholars to compare manuscripts and to search texts in ways that were previously impossible, and they have opened the field to scholars without access to the major research libraries.
The field's future is shaped by several challenges. The number of scholars trained in Avestan and Middle Persian is small, and the languages are not widely taught. The political situation in Iran, where many of the manuscripts are held, has sometimes made access difficult. And the field's traditional focus on philology has been questioned by scholars in religious studies who are more interested in theory and method. Yet the field's core questions—about the dating and interpretation of the Avesta, the nature of Zoroastrian ritual, and the relationship between the ancient and medieval traditions—remain unresolved and continue to attract new work. The texts themselves, fragmentary and difficult as they are, remain among the most important sources for the religious history of the ancient world, and their study is likely to remain a vital, if specialized, discipline.