It is to be recommended here, also, not to begin one’s studies with murder and robbery, but with the simple cases of the daily life, where there is no danger of making far-reaching mistakes, and where observations may be made much more calmly. Gestures are especially powerful habits and almost everybody makes them, mainly _not_ indifferent ones. It is amusing to observe a man at the telephone, his free hand making the gestures for both. He clenches his fist threateningly, stretches one finger after another into the air if he is counting something, stamps his foot if he is angry, and puts his finger to his head if he does not understand--in that he behaves as he would if his interlocutor were before him. Such deep-rooted tendencies to gesture hardly ever leave us. The movements also occur when we lie; and inasmuch as a man who is lying at the same time has the idea of the truth either directly or subconsciously before him, it is conceivable that this idea exercises much greater influence on gesture than the probably transitory lie. The question, therefore, is one of intensity, for each gesture requires a powerful impulse and the more energetic is the one that succeeds in causing the gesture. According to Herbert Spencer[71] it is a general and important rule that any sensation which exceeds a definite intensity expresses itself ordinarily in activity of the body. This fact is the more important for us inasmuch as we rarely have to deal with light and with not deep-reaching and superficial sensations. In most cases the sensations in question “exceed a certain intensity,” so that we are able to perceive a bodily expression at least in the form of a gesture.