I have been told that when Charles de Gaulle was asked what something he had said would mean to an ordinary Frenchman, he replied, "I do not know, I'm not an ordinary Frenchman." Similarly, I suppose I am not an ordinary reader of this book, A Religious History of the American People (Yale University Press; 1158 + xvi pp.; $19.95), but one who has for many years been surveying the same hills and valleys that Sydney Ahlstrom has traversed with camera and notebook. But while I have worked more as a topographer with the hope of making a usable map for the guidance of any who might wish to follow, Ahlstrom has pulled together an imposing slide show of the terrain and its inhabitants—a travelogue made up of thousands of discrete snapshots given unity primarily by the fact that all were taken by the same historically conditioned person.