Sergey Prokofiev, a compulsive diarist and gifted and idiosyncratic writer, possessed an incorrigibly sardonic curiosity about individuals and events. When he left Russia after the 1917 Revolution, his diaries were recovered from the family flat in Petrograd and later hidden at considerable personal risk by the composer Nikolai Myaskovsky. Prokofiev himself smuggled them out of the country after his first return to the Soviet Union in 1927. The...