Calmness of mind is one of the beautiful jewels of wisdom. It is the result of long and patient effort in self-control. Its presence is an indication of ripened experience, and of a more than ordinary knowledge of the laws and operations of thought.
Benjamin Franklin, tactless in his youth, became so diplomatic, so adroit at handling people that he was made American Ambassador to France. The secret of his success? "I will speak ill of no man," he said, ... "and speak all the good I know of everybody." Any fool can criticize, condemn and complain - and most fools do. But it takes character and self-control to be understanding and forgiving. "A great man shows his greatness," says Carlyle, "by the way he treats little men."
Let every one of us cultivate, in every word that issues from our mouth, absolute truth. I say cultivate, because to very few people — as may be noticed of most young children — does truth, this rigid, literal veracity, come by nature. To many, even who love it and prize it dearly in others, it comes only after the self-control, watchfulness, and bitter experience of years.
Dinah Craik, A Woman's Thoughts About Women, (1858) Ch. 8.
The concept of substance leads to a materialist aspect of the mind. I speak instead of the spiritual existence of the self without mentioning any 'substance' properties. The great problem is 'how the self controls its brain'. This is dualistic, but not in terms of two substances. Instead it relates to the two worlds of Popper.
In order that a "self" may exist there must be some continuity of mental experiences and, particularly, continuity bridging gaps of unconsciousness. For example, the continuity of our "self" is resumed after sleep, anaesthesia, and the temporary amnesias of concussion and convulsions.
There can be no self-government without self-discipline. There can be no self-government without self-control. There can be no liberty unless it is grounded in moral discipline and the ability to do what is right.
Whatever God gives, he “gives not the spirit of cowardliness but the spirit of power and self-control". (2 Timothy 1.7) Just as it is required of the expectant person, if his expectancy is noble and worthy of a human being, that he seeks this spirit of power and self-control, and that, just as his expectancy is laudable, he must also be one who is properly expectant, so in turn will the object of expectancy, the more glorious and precious it is, form the expectant person in its own likeness, because a person resembles what he loves with his whole soul.
The home is the first and most effective place to learn the lessons of life: truth, honor, virtue, self control, the value of education, honest work, and the purpose and privilege of life. Nothing can take the place of home in rearing and teaching children, and no other success can compensate for failure in the home.
Trees continue to vegetate, and so do live on beasts and birds; he alone lives whose mind lives not in consequence of taking on a variety of forms. All holy writ is so much burden to him who has not acquired self-control, the body is so much burden to him who knows only the anatman (no-self.)
Yogi Ramacharaka (1907/2007), The spirit of the Upanishads, Cosmo Classics, New York, p. 23
When one intends to move or when one intends to speak, one should first examine one’s own mind and then act appropriately with composure. When one sees one’s mind to be attached or repulsed, then one should neither act nor speak, but remain still like a piece of wood. When my mind is haughty, sarcastic, full of conceit and arrogance, ridiculing, evasive and deceitful, when it is inclined to boast, or when it is contemptuous of others, abusive, and irritable, then I should remain still like a piece of wood. When my mind is averse to the interests of others and seeks my own self-interest, or when it wishes to speak out of a desire for an audience, then I will remain still like a piece of wood. When it is impatient, indolent, timid, impudent, garrulous, or biased in my own favor, then I will remain still like a piece of wood.
Santideva, A Guide to the Bodhisattva Way of Life, V. Wallace and B. Wallace, trans. (1997), § 5.47
It is not worth asking how to define consciousness, how to explain it, how it evolved, what its function is, etc., because there's no one thing for which all the answers would be the same. Instead, we have many sub-capabilities, for which the answers are different: e.g., different kinds of perception, learning, knowledge, attention control, self-monitoring, self-control, etc.