There are two systems of Abhidharma, according to Tibetan tradition, lower and higher. The lower system is taught in the Abhidharmakosa, while the higher system is taught in the Abhidharmasamuccaya. Thus the two books form a complementary pair. Asanga, author of the Abhidharmasamuccaya, is founder of the Yogacara school of Mahayana Buddhism. His younger brother Vasubandhu wrote the Abhidharmakosa before Asanga converted him to Mahayana Buddhism. Yet the Kosa is written in verse, usual for Mahayana treatises, while the Samuccaya follows the traditional prose question and answer style of the older Pali Abhidharma texts. Walpola Rahula, in preparing his 1971 French translation of this Mahayana text from the Sanskrit, Chinese, and Tibetan, has brought to bear on its many technical terms his extensive background and great expertise in the Pali canon. J. W. de Jong says in his review of this work:"Rahula deserves our gratitude for his excellent translation of this difficult text." Sara Boin-Webb is well known for her accurate English translations of Buddhist books from the French. She has now made accessible in English Rahula's French translation, the first into a modern language, of this fundamental text.