How much does a leader actually matter to an organization’s success? We tend to credit CEOs, founders, and other powerful figures with shaping the institutions they lead, but historian Jared Diamond argues that we often underestimate the role of timing, circumstance, industry, and plain luck. Diamond explains his “Hamlet test,” which asks whether someone else could have achieved the same outcome or whether the leader was uniquely qualified to do it, and how it applies to many business leaders. He also explains why some leaders are able to seize a fleeting moment of opportunity, why founders can have an outsized influence on institutions, and why boards may overestimate the impact of replacing a struggling CEO. Diamond is author of Prophets, Profits, Coaches, and Kings: (When) Do Leaders Matter?