The worst vice of a fanatic is his sincerity.

Fanaticism consists of redoubling your efforts when you have forgotten your aim.

Fanatical religion driven to a certain point is almost as bad as none at all, but not quite.

As any action or posture long continued will distort and disfigure the limbs; so the mind likewise is crippled and contracted by perpetual application to the same set of ideas.

I wish there were some cure, like the lover's leap, for all heads of which some single idea has obtained an unreasonable and irregular possession.

We call Japanese soldiers fanatics when they die rather than surrender, whereas American soldiers who do the same thing are called heroes.