When Light Pierced the Darkness: Christian Rescue of Jews in Nazi-Occupied Poland, by Nechama Tec. New York: Oxford University Press. 262 pp. $19.95. Nechama Tec, an associate professor of sociology at the University of Connecticut, has chosen the path of narrow, yet intensive research into a specific area of Holocaust studies. Her study of Christian rescue of Jews in Nazi-occupied Poland is based on 65 in-depth personal interviews which she conducted with rescuers and survivors. Tec, whose memoir ``Dry Tears'' (1984) told of her own experience as a young Jewish girl passing for Polish Catholic, draws some provocative conclusions: Unpaid rescuers proved more reliable than those who did it for money. Rescuers who acted from moral conviction usually had a previous history of helping those in need. Most rescuers had not previously known the people they rescued but responded immediately to the needs of strangers. And almost all such rescuers, whatever their social class, were strongly inner-directed individuals, many of whom were often perceived as different from their communities long before the terrors of Nazi occupation put their individualism to the test. Tec's conclusions, while based on a small survey, strike one as having the ring of truth.