VI.––The Physiology Of Habit
A work of Dr. Carpenter’s was perhaps the first which gave me the clue I was in search of. In his Mental Physiology––a most interesting book,
vol 1 pg 112
by the way––he works out the analogy between mental and physical activity, and shows that the correspondence in effect is due to a correspondence in cause.
Growing Tissues form themselves to Modes of Action.––To state roughly the doctrine of the school Dr Carpenter represents––the tissues, as muscular tissue, for instance, undergo constant waste and as constant reparation. Even those modes of muscular action which we regard as natural to us, as walking and standing erect, are in reality the results of a laborious education; quite as much so as many modes of action which we consciously acquire, as writing or dancing; but the acquired modes become perfectly easy and natural. Why? Because it is the law of the constantly growing tissues that they should form themselves according to the modes of action required of them. In a case where the brain is repeatedly sending down to the muscles, under nervous control as they are, the message to have a certain action done, that action becomes automatic in the lower centre, and the faintest suggestion from outside comes to produce it without the intervention of the brain. Thus, the joints and muscles of the child’s hand very soon accommodate themselves to the mode of action required of them in holding and guiding the pen. Observe, it is not that the child learns with his mind how to use his pen, in spite of his muscles; but that the newly growing muscles themselves take form according to the action required of them. And here is the explanation of all the mountebank feats which appear simply impossible to the untrained looker-on. They are impossible to him, because his joints and muscles have not the same powers which have been produced in the mountebank by a process of early training.