New York Times subscribers* enjoy full access to TimesMachine—view over 150 years of New York Times journalism, as it originally appeared. *Does not include Games-only or Cooking-only subscribers.

A four-year-old in a suburban daycare earns a sticker every time she shares a toy. By age six, she shares less when no sticker is offered. Teachers notice the shift but struggle to explain why. A ...

Women reportedly enjoyed Immanuel Kant’s company. But even though Kant in his lectures praised the virtues of marriage as a civil institution, conjugal bliss and sexual congress were two of the many ...