The relentless, unsentimental rules of animal life are described in the rather somber sequences of a text which follows the birth and training of a grizzly cub to the time nature dictates that his mother leave him on his own. Together, they had survived a forest fire by hiding in a pool. In the passages dealing with the course and effect of the fire, the 1953 Newbery Medal winner achieves a vitality that is not in evidence at either the start or the conclusion of a book which will probably need a strong adult push before it moves with juvenile readers.