This is a delight -- a work of cartoon animation which takes us back to those early days when Disney was in his heaven and all was right with the world. It's the debut feature movie of Don Bluth, who defected from the Disney Studios three years ago, and its story, from a best-selling children's book, combines classic living line with a touch of contemporary, and fashionable, mysticism. The widowed mouse, Mrs. Brisby knows that the plow is coming early to her harvest field, but cannot leave because her son, Timothy is desperately ill. What to do? She goes to the doomy Great Owl for help; he tells her to go to The Rats. They have become super-intelligent for reasons I won't reveal here. What the films does reveal is Don Bluth's capacity for creating characters at once vivid and memorable: the Great Owl (voiced by John Carradine) aware of the imminence of his own death; Jeremy Crow (Dom Deluise), irresistibly and comically clumsy; Mrs. Brisby (Elizabeth Hartman) herself, timorous and yet resolute, a heroine in a million. Of course, the film's greatest impact will be on children -- and there are enough scares to please them. But its story also has an adult significance which is a warning that should be heeded by all.