A Starlit Somersault Downhill

As autumnal leaves fall from the trees a frolicsome rabbit receives a warning about the hardships of winter: `` `It is not wise,' the brown bear said, / `to ask of snow your daily bread.' '' He invites the rabbit to join him in sleep ``till the hills go green and rivers run.'' After a devastating first frost, the rabbit accepts the bruin's hospitality. But as his hulking friend succumbs to a profound slumber, he tosses and turns until he reaches his own conclusions: `` `It is not wise for us, dear bear, / when snow combs silver from her hair-- / and stars are shears and hills are sheep, / it will not do to fall asleep.' '' Willard's ( Pish Posh, Said Hieronymous Bosch ; A Visit to William Blake's Inn ) typically sophisticated language gains meaning through repeated readings, and her sonorous rhyming couplets impart liveliness to nature's sleeping season. Lavishly detailed, full-spread watercolors afford views of untidy woods and tousled fur--they bristle with energy even as they suggest the restlessness youngsters may experience in the deep of night, wide awake and alone. Capping Pinkney's sumptuous display is a foldout on the final spread, where the rabbit, presented on a grand scale, leaps climactically and gloriously. Ages 4-8. (Sept.)