The nature of the mind is such that the first suggestion makes a deep impression, and the following suggestion can only make little impression. Therefore, if once a person is impressed by a wrong thing and has formed a wrong opinion it is most difficult to change it. Besides there are people who sit upon their opinions. They do not hold an opinion, the opinion holds them, and once they have formed an opinion nothing can change it, for it is a dead opinion, just like a rock. Where the rock is placed, the rock lies; it is not a living being that walks and moves.