Don't knock on the door. No one's at home.

Where the poor power of the eye can no longer see the evil impulse as such because it has become too subtle, man posits the realm of goodness; and the feeling that we have now entered the realm of goodness excites all those impulses which had been threatened and limited by the evil impulses, like the feeling of security, of comfort, of benevolence. Hence, the duller the eye, the more extensive the good. Hence the eternal cheerfulness of the common people and of children. Hence the gloominess and grief - akin to a bad conscience - of the great thinkers.