H. L. Mencken was unquestionably the most provocative and influential journalist and cultural critic in twentieth-century America. The six volumes of Prejudices, published between 1919 and 1927, were both a slashing attack on what Mencken saw as American provincialism and hypocrisy and a resounding defense of the writers and thinkers he thought of as harbingers of a new frankness and maturity. Laced with savage humor and delighting in verbal...