Public and academic interest in the Yezidis, their religion and culture, has increased greatly in recent years. The study of Yezidism has also made considerable progress in recent decades. Still, several lacunae in our knowledge remain, notably concerning many concrete aspects of the textual tradition. These gaps are due in part to the fact that many elements of religious knowledge are generally not revealed to non-Yezidis. Khanna Omarkhali, a highly qualified academic who also stems from a respected Yezidi family of religious leaders (Pir), has had unique opportunities to investigate such aspects of the Yezidi tradition. This book is a comprehensive study of the Yezidi religious textual tradition, containing descriptions of many hitherto unknown aspects of the oral transmission of Yezidi religious knowledge. It presents a detailed account of the 'mechanisms' underlying various aspects of the tradition. It shows how the religious textual tradition functioned - and to a certain degree still does - in its pre-modern way, and also describes the transformations it is currently undergoing, including the issues and processes involved in the increasing trend to commit religious knowledge to writing, and indeed to create a written canon. The work contains several hitherto unpublished texts and the most comprehensive survey to date of the extant Yezidi sacred texts. It includes four maps, a glossary of terms and a list of Yezidi lineages, and is accompanied by a CD with an extensive collection of recordings of texts (208 minutes).