It comes in handy. Not until the 18th and 19th centuries did masturbation begin to develop a bad rap, as clerics and scientists branded it immoral and unhealthy. And while solitary sex eventually turned mainstream — it was the thrust of a classic Seinfeld episode — it’s still stigmatized and frequently linked to online pornography. Some say self-stimulation is a symbol of sexual freedom, but it continues to raise eyebrows. So even if old taboos may have loosened their grip, humanist disdain for selfishness now seems to be picking up where the theologians left off.