Encounters: Ten Appointments with History describes ten meetings between historically relevant individuals and, in one case civilizations, that have profoundly imprinted themselves on both their contemporary eras and what followed. Each of the subjects of this book changed the world in ways that still resonate today, from the 2,500-year-old clash between Persia and Greece on the Plain of Marathon (Chapter One) to the dangerous Cold War inflection point represented by the summit meeting of President John F. Kennedy and his arch-rival, the Soviet Union’s Nikita Khrushchev, in Vienna in 1961 (Chapter Ten). The theme that weaves through each encounter can best be labeled the Lessons of History, a refrain that is especially relevant today when those lessons are often unknown to or not well understood by our leaders and decision-makers.