Harry S. Truman kept a set of Plutarch’s writings at hand in the White House. He said that in Plutarch’s “Parallel Lives,” he could find everything worth knowing about leaders—how they behave, what makes them tick.
In the “Lives,” Plutarch (A.D. 47-120) would compare a famous Greek to a famous Roman—setting Alexander the Great, for example, next to Julius Caesar, or Demosthenes beside Cicero. It was moral portraiture; Plutarch had a genius for details. He believed that a trivial detail can reveal a man more profoundly than a great event. Cicero, for example, became alert to an unexpected subtlety of Julius Caesar’s character after noticing, one day in the Senate, the way he adjusted his forelock with one finger.
Suppose Plutarch undertook to write one of his “Parallel Lives” on the subject of Donald Trump. If Plutarch were to study the biographies of the previous American presidents, to which of them would he compare the 45th?
Mr. Morrow is a senior fellow at the Ethics and Public Policy Center.