Abstract
I will explain, how the method started, what Eilenberg and Mac Lane used it for, how Harry Appelgate gave it a categorical setting, how Jon Beck and I realized that in our setting it took a simpler form. I will go on with Michael Andre's version and how I began to write a book on the method until two questions from grad student Rob Milson started me off in a different direction that, among other things tied Andre's version together with the older ones. I will likely take two lectures.