What did people use to believe masturbation could lead to?

Explanation

In the past it has been believed that masturbation lead to blindness, insanity, sudden death, and other unpleasant diseases. Today we know that masturbation is both normal and natural, and does not have any negative repercussions. Quite on the contrary: masturbation and the orgasm it may lead to can cure head aches, because endorphins are freed in the process. There are even masturbation competitions taking place in several countries - the so-called Masturbate-a-thons.