How does CS Lewis shows the Psychology of Moral Growth in The Chronicles of Narnia?

The psychology of moral growth is best illustrated through the character of Edmund, though all the children learn and grow. They learn and mature morally through both their experiences and their interactions with Aslan.
Edmund is initially seduced by the White Witch and the Turkish delight candy that she gives him. He trusts her stories that she will give him power. He mistakes the material goods and flattery she uses to manipulate him for real love. However, when he visits her in her castle, she reveals her true character as harsh and cruel. She gets angry at him for not bringing the other children and feeds him only bread and water. Worse, she heartlessly turns forest creatures into stone, even over his protests.
Edmund repents of having been taken in by her and learns to be more careful not to judge by outward appearances. The story shows that experience is a moral teacher. Further, when the White Witch is about to kill him, Edmund learns a lesson about true nobility and sacrifice when Aslan offers to die in his place. The contrast between the witch and Aslan couldn't be sharper. Thus, through his own difficulties and the influence of Aslan, Edmund grows morally from a self-centered liar to a person who cares about others more than himself.
Through Edmund, C.S. Lewis sends a strong message that even flawed people can learn and attain moral goodness. Love, mercy, and kindness, such as that shown by Aslan, have a powerful psychological effect on others. Lewis shows these traits as having a healing and redeeming influence on all the children. In contrast, cruelty and deception are shown to be psychologically repulsive forces. In Lewis's Christian universe, love is the greatest power. From Aslan, the children learn what love truly is, and it is this grace and gift that fits the four children to eventually become rulers.