5.50 PSYCHOLOGY. 



hibitive power. Not that tlie thought of a pleasure need 

 be itself a pleasure, usually it is the reverse — nessun mag- 

 gior dolore — as Dante says — and not that the thought of pain 

 iweed be a pain, for, as Homer says, " griefs are often after- 

 wards an entertainment." But as present pleasures are 

 tremendous reinforcers, and present pains tremendous in- 

 hibitors of whatever action leads to them, so the thoughts 

 of pleasures and pains take rank amongst the thoughts 

 which have most imj^ulsive and inhibitive power. The 

 precise relation which these thoughts hold to other thoughts 

 is thus a matter demanding some attention. 



If a movement feels agreeable, we repeat and repeat it 

 as long as the pleasure lasts. If it hurts us, our muscular 

 contractions at the instant stop. So complete is the inhibi- 

 tion in this latter case that it is almost impossible for a 

 man to cut or mutilate himself slowly and deliberately — his 

 hand invincibly refusing to bring on the pain. And there 

 are many pleasures which, when once we have begun to 

 taste them, make it all but obligatory to keep up the activ- 

 ity to which they are due. So widespread and searching 

 is this influence of pleasures and pains upon our movements 

 that a premature philosophy has decided that these are 

 our only spurs to action, and that wherever they seem to 

 be absent, it is only because they are so far on among the 

 * remoter ' images that prompt the action that they are over- 

 looked. 



This is a great mistake, how^ever. Important as is the 

 influence of pleasures and pains upon our movements, they 

 are far from being our only stimuli. With the manifesta- 

 tions of instinct and emotional exjDression, for example, they 

 have absolutely nothing to do. Who smiles for the pleasure 

 of the smiling, or frowns for the pleasure of the frown ? 

 Who blushes to escape the discomfort of not blushing ? 

 Or who in anger, grief, or fear is actuated to the movements 

 which he makes by the pleasures which they yield ? In all 

 these cases the movements are discharged fatally by the 

 vis a tergo which the stimulus exerts upon a nervous system 

 framed to respond in just that way. The objects of our 

 rage, love, or terror, the occasions of our tears and smiles, 



