From the 1920s through the 1950s, H. L. Mencken was one of the best-known and most feared writers in the United States. Professionally, Mencken was a newspaperman (for the Baltimore Evening Sun), a literary and social critic who debunked pompous politicians and simple-minded Americans as belonging to the "booboisie," a magazine editor (of The American Mercury), and a philologist (as author of the unscholarly but esteemed The American Language). Temperamentally, he was a curmudgeon, iconoclast, satirist, cynic, and writer provocateur. Known for his acid wit, he spared no one and pilloried everyone. He was both ruthless and rigid, Edmund Wilson once said, and also courageous and fearless. Mencken did not suffer fools gladly, if at all, although he was probably glad for their presence because they provided fodder for his newspaper and magazine columns. He has been compared with Thomas Paine, Jonathan...