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

You need not worry or make yourself sleepless about the world. It will
go on without you. When you have avoided fanaticism, then alone will
you work well. It is the levelheaded and calm person, of good judgment
and cool nerves, of great sympathy and love, who does good work and so
does good to himself. The fanatic is foolish and has no sympathy; he
can never straighten the world, nor himself become pure and perfect.