Throughout her Volumes, Charlotte Mason sprinkles grains of insight into the question, ‘Why study ourselves’? Often she uses the term self- knowledge for this study. She says, next to the study of God, it is the most important thing a child can learn. More important than reading? More important than math? More important than writing? Evidentially.

No one says it better than Charlotte, so here are her thoughts on the subject:

                                    Children should be taught Self-knowledge.
All this may be of importance to philosophers; but what has it to do with the bringing-up of children?
A Child should know what he is as a Human Being––It is time we reverted to the teaching of Socrates. ‘Know thyself,’ exhorted the wise man, in season and out of season; and it will be well with us when we understand that to acquaint a child with himself––what he is as a human being––is a great part of education.
It is difficult to see why; surely much harm comes of morbid introspection?
Introspection is morbid or diseased when the person imagines that all which he finds within him is peculiar to him as an individual. To know what is common to all men is a sound cure for unhealthy self-contemplation. – Charlotte Mason Volume 2  p.242-243

            “Who was it that said, ‘Know thyself’ came down from heaven? It is quite true—true as Gospel. It came straight to whoever said it first.”—Life of Sir Edward Burne-Jones.
POSSIBLY we fail to give ‘effective moral training based upon Christian principles’ to young people because our teaching is scrappy, and rests mainly upon appeals to the emotions through tale and song. Inspiring as these are, we may not depend upon them entirely, because emotional response is short-lived, and the appeal is deadened by repetition: the response of the intellect to coherent and consecutive teaching appears, on the contrary, to be continuous and enduring. Boys and girls, youths and maidens, have as much capacity to apprehend what is presented to their minds as have their elders; and, like their elders, they take great pleasure and interest in an appeal to their understanding which discovers to them the ground-plan of human nature—a common possession.
            The point of view taken in this volume is, that all beautiful and noble possibilities are present in everyone; but that each person is subject to assault and hindrance in various ways, of which he should be aware in order that he may watch and pray. Hortatory teaching is apt to bore both young people and their elders; but an ordered presentation of the possibilities that lie in human nature, and of the risks that attend these, can hardly fail to have an enlightening and stimulating effect. This volume is intended as an appeal to the young to make the most of themselves, because of the vast possibilities that are in them and of the law of God which constrains them. – Charlotte Mason from the Preface for Volume 4 Book I

            “Through philosophy, man arrives at the knowledge of what is good and what is bad, what is just and what is unjust; most especially he learns what he should endeavour after, and what he should avoid; how he should order himself towards God, towards father and mother, towards his elders, towards the laws, towards strangers and superiors, towards his friends, towards wife and child and slave. She teaches humility towards God, reverence for parents, respect for the aged, obedience to law; to be in submission to authority, to love friends, to be chaste towards women. She teaches tenderness towards children and gentleness towards slaves; she exhibits to us the highest good, that in happiness our joy be measured, and in misfortune our grief restrained; in order that we be not as the beasts, unrestrained in desire as in rage. These are, I hold, some of the benefits we owe to the teaching of philosophy. For to be modest in good fortune, to be without envy, gentle in mind, to know how to extinguish evil desires, is wisdom; and the ruling of an angry spirit is the sign of no common understanding.” – Charlotte Mason Volume 5  p.384-385

            ‘Ourselves,’ a Vast Country not yet Explored.—When we think of our bodies and of the wonderful powers they possess, we say, under our breath, “Great and marvellous are Thy works, Lord God Almighty.” Now, let us consider that still more wonderful Self which we cannot see and touch as we can our bodies, but which thinks and loves and prays to God; which is happy or sad, good or not good. This inner self is, as we have said, like a vast country much of which is not yet explored, or like a great house, built as a maze, in which you cannot find your way about. People usually talk of ‘Ourselves’ as made up of Body, Mind, Heart, and Soul; and we will do the same, because it is a convenient way to describe us. It is more convenient to say, ‘The sun rises at six and sets at nine,’ then to say, ‘As the earth turns round daily before the sun, that part of the earth on which we live first gets within sight of the sun about six o’clock in the morning in March.’ ‘The sun rises and sets’ is a better way of describing this not only because it is easier to say, but because it is what we all appear to see and to know. In the same way, everybody appears to know about his own heart and soul and mind; though, perhaps, the truth is that there is no division into parts, but that the whole of each  of us has many different powers and does many different things at different times. – Charlotte Mason Volume 4  p.33-34

            Before we can have true Self-control we must know a good deal about ourselves, that is, we must get Self-knowledge. Many persons think themselves quite different from everybody else, which is a mistake. Self-knowledge teaches that what is true of everybody else is true of us also; and when we come to know how wonderful are the powers and how immense are the possibilities of Mansoul, we are filled, not with pride, but with Self-reverence, which includes reverence and pity for the meanest and most debased, because each of these is also a great Mansoul, though it may be a Mansoul neglected, ruined, or decayed. – Charlotte Mason Volume 4  p.34

            Children should learn some Laws of Thought––In another way we may endeavour to secure for the children that stability of mind which comes of self-knowledge. It is well that they should know, so early that they will seem to themselves always to have known, some of the laws of thought which govern their own minds. Let them know that, once an idea takes possession of them, it will pursue, so to speak, its own course, will establish its own place in the very substance of the brain, will draw its own train of ideas after it. One of the most fertile sources of youthful infidelity is the fact that thoughtful boys and girls are infinitely surprised when they come to notice the course of their own thoughts. They read a book or listen to talk with a tendency to what is to them ‘free-thought.’ And then, the ‘fearful joy’ of finding that their own thoughts begin with the thought they have heard, and go on and on to new and startling conclusions on the same lines! The mental stir of all this gives a delightful sense of power, and a sense of inevitableness and certainty too; for they do not intend or try to think this or that. It comes of itself; their reason, they believe, is acting independently of them, and how can they help assuming that what comes to them of itself with an air of absolute certainty, must of necessity be right? – Charlotte Mason Volume 2  p.46