THEN AND NOW (278 pp.)W. Somerset MaughamDoubleday ($2.50).
The current historical-novel bug has bitten even Somerset Maugham. With Then and Now he leaves the 19th and 20th Centuries for the first time since his Making of a Saint (1898), retreats 400-odd years to the Italy of Cesare Borgia and Niccoló Machiavelli. Then and Now is a talky, occasionally witty costume piece about Machiavelli in love and Borgia in his glory. It is also an ironical sermon on the unchanging wonders of human nature. Novelist Maugham, now 72, denies that he preaches sermons of any kind. Said he recently: "I think it is...