FIVE hundred years ago, on Dec. 10, 1513, Niccolò Machiavelli sent a letter to his friend Francesco Vettori, describing his day spent haggling with local farmers and setting bird traps for his evening meal. A typical day for the atypical letter writer, who had changed from his mud-splattered clothes to the robes he once wore as a high official in the Florentine republic.

Toward the end of the letter Machiavelli mentions for the first time a “little work” he was writing on politics. This little work was, of course, “The Prince.”

One of the remarkable things about “The Prince” is not just what Machiavelli wrote, but that he was able to write at all. Just 10 months earlier, he endured the “strappado”: Hands tied behind his back, he was strung to a prison ceiling and repeatedly plunged to the floor.

Having at the time just been given the task of overseeing the foreign policy and defense of his native city, he was thrown out of his office when the Medici family returned to power. The new rulers suspected him of plotting against them and wanted to hear what he had to say. Machiavelli prided himself on not uttering a word....