The mood of Esther Forbes's charming novel "Rainbow on the Road" is that of a sunlit summer day, variegated with thunderstorms which pass quickly, leaving behind them an even brighter landscape….

Mrs. Forbes uses not sex—there never was a purer book—or dagger to lure the reader from page to page, but relies on a skill which most modern historical novelists seem to regard as secondary, on literary style, on the ability to evoke the wonders of everyday living. In brilliant passages, so simple that their artistry is never obvious, she reveals a clear morning, the strange personality of a ballad-singer walking the highways, all the luxuriant human life that pours out upon a traveler who knocks on many doors.

In other novels Mrs. Forbes has most effectively dipped her brush in somber hues, but this novel is so lyrical, so gay that when she uses darker...