" New situations, however, do arise, requiring novel, unstereotyped responses; hence development, in the higher organisms, requires a capacity for experiment and innovation—the social correlates of variation and mutation. Social evolution is an interplay of custom with origination. Here the initiative individual—the “great man,” the “hero,” the “genius”—regains his place as a formative force in history. He is not quite the god that Carlyle described; he grows out of his time and land, and is the product and symbol of events as well as their agent and voice; without some situation requiring a new response his new ideas would be untimely and impracticable "

― Will Durant , The Lessons of History