the mental consciousness (manovinñāna) and is the material support for consciousness. Some later Theravāda works like the Visuddhimagga locate this physical basis for consciousness at the heart (hadaya-vatthu), the Pali Canon itself is silent on this issue. Some modern Theravāda scholars propose alternative notions. For example, Suwanda H. J. Sugunasiri proposes that the basis for consciousness is the entire physical organism, which he ties with the canonical concept of jīvitindriya or life faculty. W. F. Jayasuriya meanwhile, argues that "hadaya" is not meant literally (it can also mean "essence", "core"), but refers to the entire nervous system (including the brain), which is dependent on the heart and blood. Theravādins generally reject the Mahayana sutras as Buddhavacana (word of the Buddha), and do not study or see these texts (or Mahayana doctrines) as reliable sources. They reject the view that the Tipitaka is incomplete or inferior (i.e. "Hinayana") and that Mahayana texts are somehow more advanced. Theravādins traditionally believe that an awakened arahant has an "incorruptible nature" and are thus morally perfect. They have no ignorance or doubts. According to Theravāda doctrine, arahants (as well as the other three lesser ariyas: stream enterers etc.) cannot fall back or regress from their state. Modern developments The modern era saw new developments in Theravāda scholarship due to the influence of Western thought. As Donald K. Swearer writes: Although monastic education is still grounded in the study of Buddhist texts, doctrine, and the Pali language, the curricula of monastic colleges and universities also reflect subject matter and disciplines associated with Western education.Buddhist modernist trends can be traced to figures like Anagarika Dhammapala, King Mongkut, and the first prime minister of Burma U Nu. They promoted a form of Buddhism that was compatible with rationalism and science, and opposed to superstition and certain folk practices. Walpola Rahula's, What the Buddha Taught is seen by scholars as an introduction to modernist Buddhist thought and the book continues to be widely used in universities. Another modern phenomenon is Buddhist philosophers who received an education in the West, such as K. N. Jayatilleke (a student of Wittgenstein at Cambridge) and Hammalawa Saddhatissa (who received his Phd at Edinburgh), going on to write modern works on Buddhist philosophy (Early Buddhist Theory of Knowledge, 1963 and Buddhist Ethics, 1987 respectively). Henepola Gunaratana is another modern Theravāda scholar who studied philosophy in the west (at the American University). The modern encounter