But one custom overcomes another. The watchful mother sets up new tracks in other directions; and she sees to it, that while she is leading new thoughts through the new way, the old, deeply worn “_way_ of thinking” is quite disused. Now, the cerebrum is in a state of rapid waste and rapid growth. The new growth takes shape from the new thoughts: the old is lost in the steady waste, and the child is _re_formed, physically as well as morally and mentally. That the nervous tissue of the cerebrum should be thus the _instrument_ of the mind need not surprise us when we think how the muscles and joints of the tumbler, the vocal organs of the singer, the finger-ends of the watchmaker, the palate of the tea-taster, grow to the uses they are steadily put to; and, much more, both in the case of brain and of bodily organs, grow to the uses they are _earliest_ put to. This meets in a wonderful way the case of the parent who sets himself to cure a moral failing. He sets up the course of new thoughts, and hinders those of the past, until the _new_ thoughts shall have become automatic and run of their own accord. All the time a sort of disintegration is going on in the place that held the disused thoughts; and here is the parent’s advantage. If the boy return (as, from inherited tendency, he still may do) to his old habits of thought, behold there is no more place for them in his physical being; to make a new place is a work of time, and in this work the parent can overtake and hinder him without much effort. Here, indeed, more than anywhere, “Except the Lord build the house, they labour but in vain that build it;” but surely intelligent co-operation in this divine work is our bounden duty and service. The training of the will, the instruction of the conscience, and, so far as it lies with us, the development of the divine life in the child, are carried on simultaneously with this training in the habits of a good life; and these last will carry the child safely over the season of infirm will, immature conscience, until he is able to take, under direction from above, the conduct of his life, the moulding of his character into his own hands. It is a comfort to believe that there is even a material register of our educational labours being made in the very substance of the child’s brain; and, certainly, here we have a note of warning as to the danger of letting ill ways alone in the hope that all will come right by-and-by.