Actually, thinking is nothing more than firing of neurons in the brain, which is accomplished with chemical reactions, and those reactions can cause heat since they are exothermic reactions, and as we all know heat causes objects to expand, which means the brain expands against the cranial vault, and therefore thinking can cause headaches . . .
Science.
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"the people can always be brought to the bidding of the leaders. That is easy. All you have to do is tell them they are being attacked and denounce the pacifists for lack of patriotism and exposing the country to danger. It works the same way in any country."
Hermann Goering, April 1946.