Brauer had already introduced the defect of a block and opened the way towards a classification by solving all the problems in defects zero and one, and by providing some evidence for the finiteness of the set of blocks with a given defect. In 1959 he discovered the defect group, and in 1964 Dade determined the blocks with cyclic defect groups.
In 1978 Alperin and BrouA(c) discovered the Brauer category, and BrouA(c) and the author determined the blocks having a nilpotent Brauer category. In 1979, the author discovered the source algebra which determines all the other current...