\u201cA flourishing democracy next door is a scary thing for an autocrat,\u201d says Ukrainian historian Olesya Khromeychuk. Detailing the history of Ukraine\u2019s long struggle for sovereignty and freedom \u2014 against Russian tsars, communist dictators and now the Kremlin\u2019s army \u2014 she shares three lessons anybody can use to join the global fight for democracy.