Jain tradition holds that Mahavira's teaching was first organized into fourteen vast texts called the Purvas, older and, by tradition's own account, more comprehensive than the twelve or eleven Angas that make up the core of the surviving Jain scriptural canon; the twelfth Anga, the Drishtivada, is said to have contained the Purvas as one of its sections, making them formally part of the canon's structure even as their independent content was already regarded as separately ancient and separately vulnerable to loss. Each Purva reportedly treated an enormous scope of subject matter, cosmology, logic, mathematics, astrology, and metaphysics organized to a scale later commentators describe in terms of an almost unimaginable number of verses, figures that read as traditional expressions of the Purvas' totality and antiquity rather than as literal manuscript measurements.
Transmission of material this vast depended entirely on memorization by successive generations of monks capable of holding the whole body of teaching in mind, a chain that tradition records as weakening steadily after Mahavira's death, with successive teachers said to have known fewer and fewer of the fourteen texts completely until, within several centuries, no one any longer held the entire set in memory at all.