This ""Life and Times of a Caribbean Dictator"" is the first notable attempt at a definitive, balance biography of Rafael Trujillo, total ruler of the Dominican Republic for 31 years. Perhaps, as Mr. Crassweller admits, it is too soon for definition, but, since so much of the story resides not in records and memoirs but in the living memories of those who served or endured that regime, it had to be done soon or never. Balance is a different problem; as this biographer points out, in all the previous evaluations ""there is hardly more than a single instance of a judgment that is not violently emotional and extreme."" Quite possibly, in dealing with a man who persecuted and corrupted a whole people, it is always ""too soon"" to be ""impartial"", but Mr. Crassweller has certainly tried, and if nothing else, he has made his subject, in all his contradictory aspects and for all his offenses and excesses, fully believable. Whatever the possible gaps of information and errors in interpretation, one feels one knows the man behind the image and the key to both-- power. This is beyond mere judgment; it is the beginning of real understanding.