I am very sad to learn about the passing of Dietmar Schumacher. I remember him as a student from Walter Felscher's classroom in Freiburg im Breisgau. It was 50 years ago on my first visit to Germany. In the classroom Walter publicly referred to Dietmar and praised him, and the tall, shy student replied: 'mich?' I served on his doctoral committee and over the years continued to be impressed by the seriousness of his approach to mathematics. He was an important contributor to the Canada-UK collaboration that published in 1978 major advances in the application of Grothendieck's 1961 fibered categories. To facilitate those applications Pare' and Schumacher devised a flexible presentation of the basic theory in terms of what they called indexed categories. Renewed study of these ideas, in light of the later exposition by Thomas Streicher, should lead to further applications (for example to the solution of problems posed in my 1972 Perugia Notes.) The serene spirit of Dietmar Schumacher will continue to inspire those who strive to develop such unifying applications. My heartfelt condolences go to his family. Bill Lawvere [For admin and other information see: http://www.mta.ca/~cat-dist/ ]