President Trump recently declared that he won the White House in “one of the most hard fought and consequential elections in the history of our great nation.” It is not difficult to conjure elections that mattered more, like Thomas Jefferson’s in 1800, Abraham Lincoln’s in 1860 or Franklin Roosevelt’s in 1932. What is becoming difficult to find is a modern aspirant to the White House who does not think of himself or herself as the solution to a world-historical crisis.

There is no question that Mr. Trump’s political style is aberrant. But what if, all things considered, the needs of the moment are ordinary? That is the first question demanded by the foremost political virtue: prudence. Prudence is a capacity for judgment that enables leaders to adjust politics to circumstances. In extraordinary times, prudence demands boldness. In mundane moments, it requires modesty. Lincoln, the foremost exemplar of prudence in American political history, can instruct today’s voters in both ends of that continuum.

In 1838, an ordinary historical moment, a 28-year-old Lincoln warned the Young Men’s Lyceum of Springfield, Ill., that the greatest danger to American liberty would arise from leaders seeking greatness in times that did not require it. The revolutionary generation, he believed, had attained all the fame there was to be had in America. From that point on, citizens should beware leaders manufacturing crises in pursuit of legacies. The Revolution’s “field of glory is harvested,” Lincoln explained, “and the crop is already appropriated. But new reapers will arise, and they, too, will seek a field.”

A quarter-century later, as Lincoln prepared a bold stroke that helped define his own legacy — the Emancipation Proclamation — his annual message to Congress spoke of historical circumstances more grandly: “We shall nobly save, or meanly lose, the last best hope of earth.”