Moral discipline acts with the force of a law of nature.

Those subject to it yield themselves to it unconsciously; and though it shapes and forms the whole character, until the life becomes crystallized in habit, the influence thus exercised is for the most part unseen and almost unfelt.
The importance of strict domestic discipline is curiously illustrated by a fact mentioned in Mrs.Schimmelpenninck's Memoirs, to the following effect: that a lady who, with her husband, had inspected most of the lunatic asylums of England and the Continent, found the most numerous class of patients was almost always composed of those who had been only children, and whose wills had therefore rarely been thwarted or disciplined in early life; whilst those who were members of large families, and who had been trained in self-discipline, were far less frequent victims to the malady.
Although the moral character depends in a great degree on temperament and on physical health, as well as on domestic and early training and the example of companions, it is also in the power of each individual to regulate, to restrain, and to discipline it by watchful and persevering self-control.

A competent teacher has said of the propensities and habits, that they are as teachable as Latin and Greek, while they are much more essential to happiness.
Dr.Johnson, though himself constitutionally prone to melancholy, and afflicted by it as few have been from his earliest years, said that "a man's being in a good or bad humour very much depends upon his will." We may train ourselves in a habit of patience and contentment on the one hand, or of grumbling and discontent on the other.

We may accustom ourselves to exaggerate small evils, and to underestimate great blessings.

We may even become the victim of petty miseries by giving way to them.