gampopa sönam rinchen (1079-1153), a kadam monk who was a student of the lay tantric yogi milarepa, is a key figure in the kagyu tradition. he is responsible for much of the development of kagyu monastic institutions and for recording the teachings of the lineage in writing. he synthesized the mahayana kadam teachings with the tantric teachings he received from milarepa and developed a unique system of mahāmudrā which he often taught without tantric empowerment, relying instead on guru yoga.