Annen ［安然］ (b. 841): A priest of the Tendai school in Japan. He is noted as having helped establish the doctrine and practice of Tendai Esotericism. Born in Ōmi Province, he is said to have been a relative of Dengyō. He studied the exoteric and esoteric teachings under Jikaku, the third chief priest of Enryaku-ji temple on Mount Hiei, from whom he received the bodhisattva precepts in 859. After the death of Jikaku, he continued his studies under Henjō, a senior disciple of Jikaku. In 884 he became a chief instructor of Gangyō-ji temple, following Henjō, and later founded a temple called Godai-in on Mount Hiei, where he devoted himself to writing. Hence he was called the Preceptor Godai-in or the Reverend Godai-in. Annen authored more than one hundred works dealing with the exoteric and the esoteric teachings and Siddham, a medieval Sanskrit orthography. They include Questions and Answers about the Teaching and the Time, The Treatise on the Meaning of the Mind Aspiring for Enlightenment, An Extensive Commentary on the Universally Bestowed Bodhisattva Precepts, The Storehouse of Siddham, and Different Views on the Teaching and the Time. The first two works are regarded as major textbooks of Tendai Esotericism.