Fanaticism

It is a mistake to think that fanaticism can make for the progress of mankind. On the contrary, it is a retarding element creating hatred and anger, and causing people to fight each other, and making them unsympathetic. We think that whatever we do or possess is the best in the world, and what we do not do or possess is of no value. Always remember that the world is like a dog's curly tail whenever you have a tendency to become a fanatic.

Karma Yoga. New York, 1896. Complete Works, 1: 79