The means by which a society must defend the Morality necessary to its existence can only be spiritual, for it is not a question of breaches of the positive law which result in the intervention of justice and of material penalties, but of a disregard of the commands of Morality, which are not drawn up in paragraphs. Public opinion suffices to rouse the individual who despises the Moral law to an uncomfortable sense of his unworthiness; if he finds himself treated with contempt and sees disapproval and dislike in everyone's face, either he will be spurred to an effort to overcome his immoral instincts or his self-respect will suffer from the universal contempt with which he meets; and this suffering is his punishment, therefore it is the sanction of a breach of the Moral law. If public opinion does not keep careful and severe watch, such as may be termed the function of a higher moral police, then inevitably the moral tone of the whole society will sink to a lower level, and this will result in making life harder and more difficult, and in certain circumstances may lead to dissolution. This is not a theoretical assumption, but an observed fact, a lesson taught by history. It tells us of epochs in which the licentiousness of individuals, favoured by a society too dull, weak and indifferent to stand up against bad examples, succeeded in corrupting all classes. Such a period is exemplified by the fall of Rome. Common natures indulged and wallowed in every vice, the better ones felt such disgust for a life without nobility and virtue that they discarded it, and the community lost all excuse of joint responsibility and became so loosely knit together that it was incapable of common effort or sacrifice, and collapsed miserably at the first onslaught of a foreign aggressor tempted by its depravity.