Buddha - The Vinaya Pitaka, containing disciplinary rules for the Sangha of Buddhist monks and nuns, as well as a range of other texts which explain why and how rules were instituted, supporting material, and doctrinal clarification. The Sutta Pitaka (Pali; Sanskrit: Sutra Pitaka), containing discourses of the Buddha. The Abhidhamma (Skt: Abhidharma) or commentary Pitaka, containing a philosophical systematization of the Buddha's teaching, including a detailed analysis of Buddhist psychology. During the first few centuries after Gautama Buddha, his teachings were transmitted orally, but around the 1st Century CE they began to be written down. The most notable set of texts from the early period is the Pali Canon, which was preserved in Sri Lanka by the Theravada school. The sutras it contains are also part of the canon of every other Buddhist sect. Mahayana tradition brought with it a collection of new texts, composed in Buddhist Hybrid Sanskrit, many of which were also described as actual sermons of the Buddha. These include the Perfection of Wisdom Sutras, the Avata?saka, the Lotus Sutra, the Vimalakirti Sutra, and the Nirvana Sutra.