206 LAUGHTER 



conditions of men, the accompaniment, the expression of 

 the simple joy of life. It has acquired a variety of relations 

 and significations in the course of the long development 

 of conscious man but primarily it is an expression of 

 emotion, set going by the experience of the elementary 

 joys of life the light and heat of the sun, the approach 

 of food, of love, of triumph. 



Before we look further into the matter it is well to note 

 some exceptional cases of the causation of laughter. The 

 first of these is the excitation of laughter by a purely 

 mechanical " stimulus " or action from the exterior, without 

 any corresponding mental emotion of joy namely by 

 " tickling," that is to say, by light rubbing or touching of 

 the skin under the arms or at the side of the neck, or on 

 the soles of the feet. Yet a certain readiness to respond 

 is necessary on the part of the person who is " tickled," 

 for, although an unwilling subject may be thus made to 

 laugh, yet there are conditions of mind and of body in which 

 " tickling " produces no response. I do not propose to 

 discuss why it is that " tickling," or gentle friction of the skin 

 produces laughter. It is probably one of those cases in 

 which a mechanism of the living body is set to work, as a 

 machine may be, by directly causing the final movement 

 (say the turning of a wheel), for the production of which a 

 special train of apparatus, to be started by the letting loose 

 of a spring or the turning of a steam-cock, is provided, and 

 in ordinary circumstance is the regular mode in which the 

 working of the mechanism is started. The apparatus of 

 laughter is when due to " tickling " set at work by a short 

 cut to the nerves and related muscles without recourse to 

 the normal emotional steam-cock. 



Then we have laughter which is purely due to imita- 

 tion and suggestion. People laugh because others are 

 laughing, without knowing why. This throws a good deal 

 of light on the significance of laughter. It is essentially a 



