
Lionni's finest work is a careful marriage of word and illustration -they exist in perfect harmony, one element never upstaging the other. For example, he argues that in ''a true picture book'' ''the visual image is primary, the text secondary.'' On the contrary, Mr. It is clear from his unclear introduction that he does not quite grasp the significance and beauty of Mr. Lionni's art does not really need to be legitimized by Bruno Bettelheim, the eminent child psychologist. The publication of ''Frederick's Fables,'' an anthology of 13 of his best-known picture books issued between 19, should be a cause for celebration. Lionni writes and illustrates generally concern misfits who, with just the right touch of imagination, transcend their sorry circumstances.


His influence has been pervasive in the field, traceable through the efforts of William Steig, Eric Carle, Elizabeth Cleaver and Robert Kraus, among many others. A distinguished art director and graphic artist, he is a minimalist for preschoolers. Beginning with ''Little Blue and Little Yellow,'' in 1959, he has been an outstanding innovator.

(Ages 3 to 8) LEO LIONNI is a modern master of the picture book. FREDERICK'S FABLES A Leo Lionni Treasury of Favorite Stories.
