However, in 1963, he also became Extraordinary Professor of comparative Germanic linguistics at Leiden University. Cornell University invited him as visiting professor for the 1965–1966 academic year. Its research facilities as well as the opportunity to teach mainly graduate students made him decide in 1968 to accept Cornell's offer of tenure. At Cornell, he supervised a number of Ph.D. students, all of whom went on to have academic careers. After his retirement in 1989, he remained active in supervising graduate students and continuing his research. It was mainly as an emeritus professor that he wrote his important works about language contact, some of which were unfinished at his death and so published posthumously. About five years after his wife's death, which had occurred on January 26, 1993, he was diagnosed with cancer, which caused his death on February 11, 2002. Work Teacher Coetsem was able to hold his students' attention, whether they were over two hundred, as in his introductory phonetics course at the Catholic University of Leuven, or less than a dozen, seated around the big table in his Cornell office. His lectures were well planned, and he gave them with enthusiasm. In fact, he could argue a point with real passion, when his blackboard was liable to look like an abstract expressionist painting; he was not known for orthodox didactics. However, his argumentation was always clear, and he never lost the big picture, even when a student's question would send him off on a tangent. That often happened, for he welcomed questions: he took his students seriously. (The informality between teaching staff and students was another reason for him to move to Cornell.) He used those occasions to discuss problems on which his research was focusing, which often took his students to the outer edge of modern linguistic research. As a thesis supervisor, he was anything but heavy-handed. He respected his students too much to overcorrect what they wrote, and he did not mind if they took positions with which he disagreed or if they following methods that were not his. On the contrary, if their work was solid, he would help them improve it on their own terms. The variety of Ph.D. theses that he supervised is quite remarkable. Researcher Coetsem considered doing research a true, if nonreligious, calling. What he wrote was always the result of thorough study, and his carefully worded argumentation was thought out