Now that we have shown the results of habituation let us consider additional illustrations. In piano playing, the stimuli are the notes as written in the music. We see the notes occupying certain places on the scale of the music. A note in a certain place means that we must strike a certain key. At first the response is slow, we have to hunt out each note on the keyboard. Moreover, we make many mistakes; we strike the wrong keys just as we do in typewriting. We are awkward, making many unnecessary movements, and the work is tiresome and fatiguing. After long practice, the speed with which we can manipulate the keys in playing the piano is wonderful. Our playing becomes accurate, perfect. We do it with ease, with no unnecessary movements. We can play the piano, after we become skilled, without paying attention to the actual movements of our hands. We can play the piano while concentrating upon the meaning of the music, or while carrying on a conversation, or while thinking about something else. As a rule, pleasure and confidence come with skill. Playing a difficult piece on the piano involves a skill which is one of the most complicated that man achieves. It is possible only through habituation of the piano-playing movements. Nailing shingles on a roof illustrates well the various aspects of habituation. The expert carpenter not only nails on many more shingles in a day than does the amateur, but he does it better and with more ease, and with much less fatigue. The carpenter knows exactly how much he can do in a day, and each particular movement is certain and sure. The carpenter has confidence in, and usually prides himself on, this ability, thus getting pleasure out of his work. The operations in arithmetic illustrate most of the results of habituation. Practice in addition makes for speed and accuracy. In a few weeks' time we can very much increase our speed and accuracy in adding, or in the other arithmetical operations. The foregoing examples are sufficient, although they could be multiplied indefinitely. Almost any habit one might name would show clearly most of the results enumerated. The most important aspects of habituation may be summed up in the one word _efficiency_. Habituation gives us speed and accuracy. Speed and accuracy mean skill. Skill means efficiency.