Since its publication in 1939, countless would-be readers of "Finnegans Wake" - James Joyce's masterwork, which consumed a third of his life - have given up after a few pages, dismissing it as a "perverse triumph of the unintelligible. " In 1944, a young professor of mythology and literature named Joseph Campbell, working with Henry Morton Robinson, wrote the first "key" or guide to entering the fascinating, disturbing, marvelously rich world of "Finnegans Wake. " The authors break down Joyce's "unintelligible" book page by page, stripping the text of much of its obscurity and serving up thoughtful interpretations via footnotes and bracketed commentary. They outline the book's basic action, and then simplify -- and clarify -- its complex web of images and allusions. "A Skeleton Key to Finnegans Wake" is the latest addition to the "Collected Works of Joseph Campbell" series.