Sometimes the smallest of things can illuminate the largest. A fossil tells the story of massive planetary change, a line or two of poetry does more to explain trench warfare than a dozen history books, and the miniatures of Nicholas Hilliard bring Gloriana’s long vanished England back to iridescent, dangerous life. In writing “Lenin’s Brain” (Hoover Institution Press, 163 pages, $15), Houston University professor Paul R. Gregory has mined the Hoover Institution’s extraordinary collection of Soviet archival material to come up with 14 brief, deftly chosen tales that brilliantly illuminate the cruelties, the absurdities, and the failures of the USSR’s [...]