On arrival in Tibet, Atiśa found that Buddhism was only beginning to reassert itself there following the earlier persecution by King Langdarma, and that the monks lacked guidance on interpretation of the ‘old’ tantras such as Atiśa found at Samye, and the ‘new’ tantras being freshly introduced by the great traveller-translators such as Rinchen Zangpo. Atiśa's main task was to correct their superficial interpretations. Atiśa accomplished this essentially by emphasizing monastic discipline, the grounding of Tantrism in the philosophy and ethics of the sūtras, and the need for a pupil to devote himself to a single teacher. Atiśa is credited with the introduction into Tibet of the worship of Tārā, and of the popular system of meditation and philosophy known as Lojong (blo.sbyong, ‘mind training’), which involves such meditations as the consideration of all beings as having been one's mother in a previous existence. Of more than 200 works ascribed to Atiśa, his most famous is Bodhipathapradīpa (A Lamp for the Path to Enlightenment), elucidating the correct development of the bodhisattva.
"Atiśa." The Concise Oxford Dictionary of World Religions. . Encyclopedia.com. (September 25, 2017). http://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/atisa
"Atiśa." The Concise Oxford Dictionary of World Religions. . Retrieved September 25, 2017 from Encyclopedia.com: http://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/atisa