Countless would-be readers of 'Finnegans Wake' - James Joyce's 1939 masterwork, on which he labored for a third of his life - have given up after a few pages and dismissed the book as a perverse triumph of the unintelligible." In 1944, a young professor of mythology and literature named Joseph Campbell, working with novelist and poet Henry Morton Robinson, wrote the first guide to understanding the fascinating world of 'Finnegans Wake'. Page by page,...