" No man can concentrate his attention upon evil, or even upon the idea of evil, and remain unaffected. To be more against the devil than for God is exceedingly dangerous. Every crusader is apt to go mad. He is haunted by the wickedness which he attributes to his enemies; it becomes in some sort a part of him.
Possession is more often secular than supernatural. Men are possessed by their thoughts of a hated person, a hated class, race or nation. At the present time the destinies of the world are in the hands of self-made demoniacs - of men who are possessed by, and who manifest, the evil they have chose to see in others. They do not believe in devils; but they have tried their hardest to be possessed - have tried and been triumphantly successful. And since they believe even less in God than in the devil, seems very unlikely that they will ever be able to cure themselves of their possession. Concentrating his attention upon the idea of a supernatural uncommon among secular demoniacs. But his idea of good was also supernatural and metaphysical, and in the end it saved him. "

― Aldous Huxley , The Devils of Loudun