Scholar of Aramaic, Syriac, and religions of Late Antiquity. He was Professor of Semitic Languages and Cultures and the Archeology of the Near East at the University of Groningen (The Netherlands). After his edition of the ‘Book of the Laws of Countries’ and his dissertation on Bardaiṣan of Edessa (1966), his broad and varied interests in Syriac studies were particularly focused on the language, literature, culture, and religion of early Syriac Christianity and its center, the city of Edessa. His many publications in this field concern among other things the pagan religions in Edessa and Syria, Judaism, Gnosticism, Christian heresies, Manichaeism, Marcionism, and early Syriac literature such as the Odes of Solomon, the works of Ephrem , and the Teaching of Addai. A special field of attention is represented by his studies of Aramaic inscriptions, in particular the Old Syriac inscriptions of Edessa and Osrhoene. Collections of his scholarly articles were published in 1984 and 1994. Two Festschrifts were offered to him in 1999.