These legends were continually introduced into the religious discourses of the Buddhist teachers to illustrate the doctrines of their faith or to magnify the glory and sanctity of the Buddha, somewhat as medieval preachers in Europe used to enliven their sermons by introducing fables and popular tales to rouse the flagging interest of their hearers.
Sculptured scenes from the Jatakas, found upon the carved railings around the relic shrines of Sanchi and Amaravati and of Bharhut, indicate that the 'Birth-stories' were widely known in the third century B.C., and were then considered as part of the sacred history of the religion.
At first the tales were probably handed down orally, and it is uncertain when they were put together in systematic form.
While some of the stories are Buddhistic and depend for their point on some custom or idea peculiar to Buddhism, many are age-old fables, the flotsam and jetsam of folklore, which have appeared under various guises throughout the centuries, as when they were used by Boccaccio or Poggio, merely as merry tales, or by Chaucer.
