ABSTRACT
While we were at Columbia we prepared a careful, systematic exposition of these ideas in a manuscript titled, “The General Theory of Natural Equivalences,” which we submitted to the Transactions of the American Mathematical Society. Paul Smith was the current editor who knew Sammy well from common interests in topology, so Sammy talked to him about possible referees for our paper on categories. Sammy suggested his young friend George Mackey, who, as a former student of Marshall Stone, was definitely interested in abstract ideas. I do not recall what was in his referee report, but the paper was accepted by the Transactions. As a result, the general theory of categories was published in a timely way, proudly discovering very general conceptual aspects of mathematics. At the time, we sometimes called our subject “general abstract nonsense.” We didn’t really mean
the nonsense part, and we were proud of its generality. At the time, Sammy decreed that there was no need for further publication on categories-with functors and natural transformations, it was all already there.
