Short answers, pulled from the story.
David Seyfort Ruegg (the 1st of August 1931 - the 2nd of February 2021) was an American-British Buddhologist who specialized in Madhyamaka philosophy, a core doctrine of Mahayana Buddhism. His career extended from the 1950s across more than six decades, and scholar L. S. Cousins called him "certainly the leading scholar today" on tathâgatagarbha doctrine.
Ruegg's specialty was Madhyamaka philosophy, a central doctrine of Mahayana Buddhism, and the related concept of tathâgatagarbha. He produced major works on both, including "The literature of the Madhyamaka school of philosophy in India" (1981) and his Sorbonne doctoral thesis on tathâgatagarbha published in 1969.
Ruegg graduated from the École des Hautes Etudes in 1957 with degrees in historical science and Sanskrit. He then earned a second doctorate in linguistics from the Sorbonne in Paris, where his thesis focused on the Buddhist doctrines of tathâgatagarbha and gotra.
Ruegg joined the Ecole Francaise d'Extreme Orient in 1964, then held the Chair of Languages and Cultures of India and Tibet at Leiden University from 1966 to 1972. He later became associated with the School of Oriental and African Studies at the University of London, and served as president of the International Association of Buddhist Studies from 1991 to 1999.
Ruegg died from complications of COVID-19 in London on the 2nd of February 2021, during the COVID-19 pandemic in England. He was 89 years old.
Among his major works are "La théorie du tathâgatagarbha et du gotra" (1969), "The literature of the Madhyamaka school of philosophy in India" (1981), and "Buddha-nature, Mind and the problem of Gradualism in a comparative perspective" (1989), based on the Jordan Lectures he delivered in 1987. He also published an early study of the Tibetan scholar Bu ston Rin po che in 1966.