These doctrines have survived in the great Russian sects, and can be traced back to the teachings and practice of the Bogomils. But in addition to these doctrines of an adoptionist origin, they held the Manichaean dualistic conception of the origin of the world. This has been partly preserved in some of their literary remains, and has taken deep root in the beliefs and traditions of Balkan nations with substantial Bogomil followings. The chief literature of all the heretical sects throughout the ages has been that of apocryphal Biblical narratives, and the popes Jeremiah or Bogumil are directly mentioned as authors of such forbidden books "which no orthodox dare read". Though these writings are mostly of the same origin as those from the older lists of apocryphal books, they underwent a modification at the hands of their Bogomil editors, so as to be useful for the propagation of their own specific doctrines.