The article applies K. Hempel’s logical scheme for full-fledged academic explanation of the origin and flourishing of humanism in the Northern Italy city-states (15th–16th centuries). Large consolidated continuous ideological movements (including Italian humanism) arise not randomly but because of combined circumstances in various social spheres (from geopolitics to everyday practices). Author’s formulation of the “universal hypothesis” (for genesis of any cultural movements) uses Toynbееаn “challenge-response” scheme, the principle of positive reinforcement of successful response strategies, the concepts of legitimacy, social movements, and resource mobilization. The genesis of Italian humanism is conceptualized as a macro-event with a fixed set of well-known ideological characteristics (anthropocentrism, activism, the “renaissance” of Roman and Greek classics, hedonism, faith in magic, etc). Initial data include main challenges-threats and challenges-opportunities for the Italian elites and the papacy, characteristics of affordable cultural capital (Latin and Greek “antiquities”). Also ensuing cultural strategies were successful. The movement gained sources of replenishment by young newcomers, rich high-ranking patrons with plenty of cultural resources. Non-institutionalized channels of vertical mobility were open in diplomacy, papal bureaucracy, commerce, literacy, art, and education. The correspondence of these initial data for the late 15th century Italy with the universal hypothesis premises means an obligatory appearance of macro-events: emergence and flourishing of humanism as a cultural movement with given characteristics.