PSYCHOLOGY 289 



nor the physical horror which many animals show for certain 

 unpleasant odours be set on the same plane as moral loathing. 



Wundt, 1 who held that emotional expressions arose from the 

 action of the feelings upon the progression of ideas, distinguished 

 two classes of movements for the expression of the emotions. 

 Affective (reflex or purely expressive) movements, arising from 

 the direct stimulation of the mind by an impression, and im- 

 pulsive (impulse) movements, the result of internal or external 

 stimuli, which excite a succession of ideas whose outcome is the 

 production of definite feelings. Impulsive movements will be 

 discussed later on ; at present we may confine our attention to 

 the affective movements, or those expressions of emotion which 

 manifest by expressive movement certain psychical affective 

 states. Although the number of mimetic movements is very 

 small in comparison with the multitude of emotions and moods, 

 it is very difficult to give an adequate psycho-physiological ex- 

 planation of them. According to Herbert Spencer, 2 there is a 

 general law that feeling passing a certain pitch, habitually vents 

 itself in bodily action, and that an overflow of nerve-force un- 

 directed by any motive, will manifestly take first the most 

 habitual routes ; and if these do not suffice will next overflow 

 into the less habitual ones. 



Already physiology had independently tried to arrive at a 

 scientific instead of a philosophical explanation of the movements 

 of expression ; but Johannes Miiller, the greatest of the older 

 physiologists, declared in his Text-book of Human Physiology 

 that it was utterly impossible to find an explanation why various 

 groups of fibres of the facial nerve are stimulated according to 

 the mental mood. 



Darwin 3 did not allow this statement to deter him from 

 making further research. He adopted three principles applic- 

 able to the influence of mental emotions, or involuntary feelings, 

 upon men or animals. The first is the principle of serviceable 

 associated habits, as for instance a hungry horse pawing the 

 ground, or the huddling together of frightened animals and 

 men. The second is the principle of antithesis, and this seems 



1 Wundt, loc. cit., p. 381. 



2 Spencer, Essays : Scientific, Political and Speculative. Second series, 1863, 

 p, in. 



3 Darwin, The Expression of the Emotions, London, John Murray, p. 28 et seq. 



