The specter of masturbation had long haunted the authorities. For centuries, it had been linked to mental illness at worst and a sort of general dissipation at best. (It was draining, you see.) In 1760, the Swiss physician Samuel Auguste Tissot wrote the founding text of masturbation anxiety, the sky-is-falling opus L’Onanisme, in which self-stimulation leads inexorably to physical decrepitude. (This is scarcely an exaggeration.)
But at the turn of the twentieth century, this anxiety is expressed not in the faux-medical language of Tissot and his followers but in the new scientific language of child-rearing. Imagine opening up your modern parenting book by Harvey Karp or your T. Berry Brazelton and reading that your baby touching himself, however idly, threatened his entire future.
via How to Address the Masturbating Child – Nicholas Day – The Atlantic.