The second great law of habit formation is the law of effect. This law says that any connection whose activity is accompanied by or followed by satisfaction tends thereby to be strengthened. If the accompanying emotional tone is annoyance, the connection is weakened. This law that satisfaction stamps connections in, and annoyance inhibits connections, is one of the greatest if not the greatest law of human life. Whatever gives satisfaction, that mankind continues to do. He learns only that which results in some kind of satisfaction. Because of the working of this law animals learn to do their tricks, the baby learns to talk, the child learns to tell the truth, the adult learns to work with the fourth dimension. Repetition by itself is a wasteful method of habit formation. The law of effect must work as well as the law of exercise, if the results are to be satisfactory. As has already been pointed out, it is not the practice alone that makes perfect, but the _stressing_ of improvements, and that fixing is made possible only by satisfaction. Pleasure, in the broad sense, must be the accompaniment or the result of any connection that is to become habitual. This satisfaction may be of many different sorts, physical, emotional, or intellectual. It may be occasioned by a reward or recognition from without or by appreciation arising from self-criticism. In some form or other it must be present. Two further suggestions in habit formation which grow out of the above laws should be borne in mind. The first is the effect of primacy. In everyday language, "first impressions last longest." The character of the first responses made in any given situation have great influence on all succeeding responses. They make the strongest impression, they are the hardest to eradicate. From a physiological point of view the explanation is evident. A connection untraversed or used but a few times is much more plastic than later when it has been used often. Hence the first time the connection is used gives a greater set or bent than any equal subsequent activity. This is true both of the nervous system as a whole and of any particular conduction unit. Thus impressions made in childhood count more than those of the same strength made later. The first few attempts in pronouncing foreign words fixes the pronunciation. The first few weeks in a subject or in dealing with any person influences all subsequent responses to a marked degree.