Once, when my parents were visiting, I broke this tacit compact on a drive to Philadelphia with my mother and her cousin Janet. Janet and her son had been in a heated email exchange about whether Israel was an apartheid state, and then, she said, his emails had simply stopped coming. “Well, and so we shall cease to speak of such things, and our generation shall rise,” I snapped from the back seat, like I was suddenly the Bible or something. Everyone was quiet; it isn’t nice to tell people they will be swept away by time.