There exists a creature which is perfectly harmless; when it passes before your eyes you scarcely notice it and forget it again immediately. But as soon as it invisibly gets somehow into your ears, it develops there, it hatches, as it were, and cases have been known where it was penetrated even into the brain and has thriven devastatingly in that organ, like those pneumococci in dogs that gain entrance through the nose.This creature is one’s neighbor.