“While the natural instincts of democracy lead the people to banish distinguished men from power,” Tocqueville wrote in Democracy in America, “an instinct no less powerful leads distinguished men to shun careers in politics, in which it is so very difficult to remain entirely true to oneself or to advance without self-abasement.” Some 170 years and 36 presidents later, the choice presented to the American people at this year’s presidential election does not merely confirm the correctness of the Frenchman’s assessment; it amplifies his verdict in an absurd, almost surreal manner. Among America’s presidents—many of them impressive and some great,...