If this set of essays, written in 1990, is judged as an attempt to size up the first five years of the Gorbachev era, it helps to consolidate criteria for making judgments, to single out major features of change in the Soviet Union, for good and ill, and to compare the effects of perestroika on society, culture, politics, economics and foreign policy. If, however, it is judged as an explanation for why the history of the Soviet Union has taken the dramatic turn of the last several months, the reader will have trouble finding a clear set of roots.