Black Magic is Not a Myth in Articles by Aleister Crowley.
“One day, without warning, I woke up to find that I had lost all my maturity. I became mentally and physically a stupid stripling. The only thing I could think of doing was to cut down trees!
I was living in a cottage in New Hampshire; for fifteen hours a day I toiled at felling trees. I worked like a madman. No feat of strength was too great for me.” [via, also]