Sin as an idea, it seems, has a way of changing with the times. Karl A. Olsson in an introduction to Seven Sins and Seven Virtues traces this kaleidescopic concept from its earliest Christian significance where sin was very definitely related to the idea of living as Jesus lived through its various emphases and theological status; it is now a minority religion confronted by increasingly hostile leaders, to many of whom communism seems the most urgent and plausible way of life for the immediate future. Dr. G. McLeod Bryan, professor of Christian Ethics at Wake Forest College spells out why this may be so after extended special study on the African continent. He writes as a concerned Christian, calling on the Church to become involved in the political and social issue of Africa that she may work as partners with the new leaders to whom the future belongs. All Christians who wonder why so much of the world seems to be making an ungrateful response to many years of missionary effort should study this book calling for a new approach to the problem before time runs out.