THE TWENTIES by EDMUND WILSON 557 pages. Farrar, Straus & Giroux.
Posterity's revenge on writers who overshadow it is to turn them into monuments. In the case of Edmund Wilson, the process was well under way two years ago when he died at 77already muffled in a banner bearing the legend "Distinguished Man of Letters." But here, in The Twenties, Wilson's ghost puts in a timely appearance that should forestall too much venerationbreaking out the gin, putting a record on the Victrola and eagerly looking over every pretty flapper in the room.