Ennin (794-864)

Early Tendai monk and third abbot of the Enryakuji, the main temple and headquarters of the school on Mt. Hiei. He began training with Tendai founder Saichō at age 15. In 838 he travelled to China, and remained there until 847, studying all aspects of Buddhism including Sanskrit language, esoteric rites, Ch'an and T'ien-t'ai meditation techniques among others. His sojourn spanned the Hui-ch'ang persecution of 845, and the diary he kept during this time provides an invaluable historical source for that period. His promotion of the T'ien-t'ai ‘constantly walking’ meditation, which centres upon chanting the name of the Buddha Amitābha and seeking a vision of him, helped establish Pure Land practice as a part of the Tendai repertoire and laid the groundwork for the later development of the Pure Land schools.

A Dictionary of Buddhism, Oxford University Press, 2003, 2004 (which is available in electronic version from answer.com)