Less a biography than a celebration of the power of prayer; a well-intentioned, though somewhat simplistic, portrait of the missionary nun who has in recent years joined Gandhi, Schweitzer and King as one of the great humanitarian ""saints"" of the 20th century. The brief, 120-page narrative may prove uplifting to those already convinced of the efficacy of prayer and the need for faith; more skeptical readers are likely to find the author's hagiographic approach and lack of psychological probing frustrating. No one, no matter what his or her religious impulses (or lack of them), can deny the contributions of this ""servant of the poorest of the poor"" to the alleviation of suffering not only in India, where she makes her headquarters, but around the world. Her accomplishments are widely recognized, earning, among other honors, the Nobel Peace Prize in 1979. Disappointingly, the mechanics by which Mother Teresa and her fellow Missionaries of Charity brought these accomplishments to fruition are left largely unexplored here. Mother Teresa herself attributes her success to divine intervention, and it would seem she has reason to believe so. According to Porter, problems arise, Teresa prays, the difficulties evaporate. God may indeed ""work in mysterious ways,"" but such an explanation presents something of a biographical dead-end. The nun's unquestioning faith and her trust in God's will certainly are admirable, but the reader, eager for personal insights into the woman, is bound to wish for more information about the hows and whys. Merely to be told that Teresa displayed charitable inclinations and a devotion to the Virgin Mary at an early age and that she led a normal childhood in a family noted for its closeness and religiosity isn't enough. Porter's prose does little to enliven the narrative. He seldom describes locales, rarely delves beneath the surface, resolutely refuses to ""dramatize"" the material. Part of the problem may stern from the fact that he is drawing on the reminiscences of Teresa's cousin, whose biography of the nun was published in Albanian a few years back. Too, Teresa's steadfast refusal to reveal her own personality, preferring to focus attention on the spiritual and the supernatural, may account for the paucity of details. Whatever the causes, the whole story remains to be told.