This story of the Nativity, written by a 16th-century Spanish missionary in the Aztec language, is the rare antiquarian find that belongs in a children's picture book--perhaps because it was composed for a people with a living oral tradition and recited, as we learn, to the accompaniment of drums. The language is simple, direct, graphic; the details are striking, unusual (some from medieval European legends, Bierhorst notes, some from Aztec lore); the narrative consists of short sentences, dialogue, invocation. We first hear that, though many people lived ""good lives"" before Jesus, they did not ""have the power to save either themselves or anyone else from the hands of the devil."" That was what Jesus did when he came to earth. In the book's most memorable sequence, a flock of angels appears over Bethlehem: ""The angels came down from the sky like birds. Their voices were bells. They sounded like flutes. 'Praise God in heaven, alleluia.'"" They scatter ""sweet-smelling song-flowers. . . in a golden rain."" (""Let's scatter these golden flowers, alleluia."") ""Emeralds, pearls and red crystals are glowing. They're glistening. It's dawn. 'Alleluia.'"" (The librarian with a keen ear might hear Margaret Wise Brown.) Cooney's demure figurines, jewel tones, and spun-sugar skies are surprisingly effective as a vehicle for illustrating these varied marvels--probably on account of her blend of solemnity and naivetÃ‰. The setting is Mexico, with its own bare landscapes and rich, mixed tradition of decorative art. Sometimes close to exquisite, sometimes almost monumental, the illustrations in any case give a concrete and convincing, non-Holy Land embodiment to a text whose cultural and dramatic differences enhance the Nativity story.