PLEASURE AND PAIN 61 



Both sets of feelings have played a leading part in 

 evolutionary and ethical theories : they have, it 

 is said, served us as guides for the avoidance of 

 what is harmful and the embracing of what is 

 useful, in the struggle for life, and in our conscious 

 behaviour. These theories assume that the useful 

 invariably excites pleasure and never pain, and 

 that the harmful invariably excites pain and 

 never pleasure. This assumption appears to 

 outrun the facts. Generally, it is true, we eat 

 wholesome food with pleasure, and dislike things 

 which would disagree with us. But all human 

 likings are certainly not to be classed as bene- 

 ficial : some are indeed harmful beyond doubt, 

 such as the passion for intoxicants or for gambling, 

 and the depraved refinements of lustful desire. 

 It is not only man's tastes that may be perverted. 

 Sheep and partridges may become exceedingly 

 filthy feeders : a New Zealand parrot has within 

 recent years become carnivorous. There are 

 plants, such as Venus's Fly-trap (Dionsea) and the 

 Pitcher-plant (Nepenthes), which capture flies 

 and feed upon them ; but they appear to flourish 

 equally well when this diet is denied them. The 

 smell of putrid fish is to most men disgusting : 

 yet to millions of mankind fish in this condition 

 is an enjoyable article of diet. Many of our likes 

 and dislikes are unconnected with utility or 

 harmfulness. Why, for instance, does the touch 

 of slime repel us, the squeaking of a slate pencil 

 set our teeth on edge ? Why are some persons 

 uneasy if a cat is in the room ? Why are women 

 so commonly frightened of a mouse ? An instinct 

 or a feeling which interfered with the efficiency of 

 an organism, would generally be eliminated in the 

 course of evolution ; but should, in the exuber- 

 ance of Life's activity, instincts or feelings arise 

 which are neither useful nor harmful, which may 



