120 MIND IN EVOLUTION CHAP. 



of the yellow and black caterpillar." We may be content 

 to point out that a movement of rejection, a movement 

 adapted to getting rid of a nasty taste, is evoked by the 

 sight of the caterpillar just as it was in the original ex- 

 perience by its presence in the chick's mouth. In the same 

 way, to swallow very disagreeable food may produce in us 

 retching or actual sickness, and if the impression is very 

 strong, the mere sight or even the bare idea of such food 

 may subsequently produce a certain feeling of nausea, or 

 perhaps evoke gestures expressing violent rejection. 



The upshot of these considerations is that the pain felt 

 in such cases, 1 is the expression in consciousness 2 of inhibi- 

 tory movement withdrawal, shrinking, flight, rejection, 

 whatever it may be that is best adapted to cutting short 

 the effect of some stimulus, or some reaction which one 

 has incautiously made. Conversely, pleasure is the ex- 

 pression of confirmatory movement tending to prolong the 

 reaction, or carry it out strenuously to its final develop- 

 ment to swallow with gusto, or to expose more and more 

 of the surface to the pleasing contact. 



5. From this slight account, we can gather a certain 

 conception, however inadequate, of the nature of the change 

 whereby experience modifies a reaction. The first point 

 which emerges clearly is that the inhibitory movement, 

 which on a superficial view may seem to appear for the 

 first time after the organism has once had a " painful " 

 experience, really first appears in the first experience itself, 

 and is merely repeated under somewhat modified con- 

 ditions, and accordingly with different results, in the later 

 experiences. Let us analyse this modified repetition. 

 The sight of the cinnabar caterpillar was at first a stimulus 

 to pecking. The result of the peck was the taste? and 

 the taste involved the movement of rejection. But the 

 taste also of course involved contact of the food with the 



1 I am far from saying that there is no other source of feeling than the 

 motor reaction to sense stimulus. 



2 The term " expression " is meant to convey a concomitance of the 

 intimate nature of which we are ignorant, though we know it must be 

 something other than bare concomitance. 



3 The word is used, of course, with the provisions and on the grounds 

 explained above (Chapter II). 



