The collapse of the January 1863 Uprising prompted an agonizing reappraisal of Poland's situation. Poles gave up their earlier practice of "measuring their goals by their aspirations" (Adam Mickiewicz) and buckled down to hard work and study. "[A] Positivist," wrote the novelist Bolesław Prus's friend, Julian Ochorowicz, was "anyone who bases assertions on verifiable evidence; who does not express himself categorically about doubtful things, and does not speak at all about those that are inaccessible."