The younger category theorists will have had little knowledge of the great contributions Alex made in the early days. Not research in category theory per se, but an early promoter, supporter, and consumer of category theory in algebraic topology. See his paper in the La Jolla volume. I believe that he was also one of the organizers of that meeting. When I arrived in Urbana in the fall of 1964, there was an active seminar in category theory. Alex, Jon Beck, Max Kelly, John Gray and I were the main participants along with graduate students. Mac Lane's invitation to the five of us to spend a weekend in Chicago constituted the first mid-west category meeting. Then came the La Jolla meeting. Unfortunately, at the end of that year, Alex went off to CUNY, Jon to Cornell, Max back to Sydney and John and I were left alone. Alex was really the third established mathematician (after Eilenberg and Mac Lane, of course) to embrace category theory in that way. We mourn his passing.