I am relieved to report that ["Foundation's Edge"] is a worthy sequel in every way. As before, the First Foundation wields the power of the physical sciences and technology, and the Second Foundation has the power to cloud men's minds and predict mass behavior through the statistical insights of psychohistory. Also as before, the fate of all humanity is at stake as these mighty adversaries clash—and the focus is on the actions of a handful of people who are earnest and articulate and likable even when they do bad things (for what seem to them good reasons). Mr. Asimov gives us adversaries but no villains; this is future history portrayed as a great game. The danger of such a concept is that the reader will cease to care who wins or loses. Mr. Asimov sustains interest by keeping us guessing just which side each player represents. He...