Stories, ballads, anecdotes, and episodes that tell about the previous lives of the Buddha, in both human and animal form, are called Jatakas. Jataka is a Pali and Sanskrit word that means “birth.” The Buddha, it is believed, used these tales to stress the importance of human values, which contribute to harmony and progress, and to explain concepts such as rebirth. The stories, each containing a moral, were kept alive for centuries by word of mouth before they were written in verse and prose form.Each tale begins by noting the occasion that prompted its telling and ends with the Buddha identifying the lives of the people in the story with those of people from the past. There is humor in these stories and considerable variety. The future Buddha may appear in them as a king, an outcast, a god, or an elephant; in whatever form, he exhibits some virtue that the tale thereby teaches.Many of the Jatakas have parallels in non-Buddhist Indian literature, including the Mahabharata (Great Epic of the Bharata Dynasty), the Pancatantra (animal fables), and the Puranas (a collection of Sanskrit legends). Some turn up again in such places as Aesop's fables. The Jataka stories have also been illustrated frequently in sculpture and painting throughout the Buddhist world.