The first Joseph Campbell book I read was A Skeleton Key to Finnegans Wake. Joycean scholars were somewhat annoyed that Campbell was barging into their territory, but I think that he is actually the ideal tour guide for Finnegans Wake, which absorbed stories and myths from many different cultures , many different times. His opening paragraph is still one of the best summaries of the Wake that I know of:
Running riddle and fluid answer, Finnegans Wake is a mighty allegory of the fall and resurrection of mankind. It is a strange book, a compound of fable, symphony, and nightmare-a monstrous enigma beckoning imperiously from the shadowy pits of sleep. Its mechanics resemble those of a dream, a dream which has freed the author from the necessities of common logic and has enabled him to compress all periods of history, all phases of individual and racial development, into a circular design, of which every part is beginning, middle, and end.
And believe it or not, that is a real cosmic object, in fact it is...