I think I know man, but as for men, I know them not.
—Jean-Jacques Rousseau
It is said that the single ornament adorning the walls of Immanuel Kant’s sparsely furnished study was a portrait of Jean-Jacques Rousseau. Tradition also has it that the only occasion on which Kant neglected his daily walk—proverbially so punctual that his neighbors in Königsberg set their watches by it—was in 1762 when Rousseau’s novel Émile appeared and Kant sat reading it the whole day, utterly enthralled. What did the philosopher find so appealing about Rousseau? One would be hard pressed to think of two more divergent personalities. The chaste, dutiful, overwhelmingly intellectual Kant and the famously erratic Rousseau, with his personal excesses, his celebration of feeling and sentiment, and his strident pronouncements about the corrupting effects of modern civilization: they could not have been more at odds with each other. Yet Kant credited Rousseau with a great deal. “I am myself an inquirer by inclination,” he wrote when he was forty. “I feel a consuming thirst for knowledge and a restless passion to advance in it . . . . There was a time when I thought this alone could constitute the honor of mankind, and I despised the common man who knows nothing. Rousseau set me right.”
In essence, what Kant gleaned from Rousseau was a new appreciation of the part that freedom and feeling play in man’s moral life. He learned that reason, even if it was the key to