192 ETHICAL ASPECTS OF EVOLUTION 



disputes the wisdom of his choice, and there is no way of 

 deciding the argument. Marking would not help him, 

 as the number of marks to be assigned would be deter 

 mined by no external standard, and would vary with every 

 change of mood, and every individual. If, however, we 

 had a tape or a clock or a thermometer, or some other 

 instrument to perform for gradations of pleasure what those 

 instruments do for space, time, and heat, hesitation, 

 repentance, and dispute, would all alike be impossible. 

 Even in the barely conceivable case of the exact numerical 

 equivalence of two conflicting pleasures, the demonstration 

 of complete indifference would justify the choice of either. 

 The dilemma of the bank clerk seems to me to be typical 

 of all cases in which we wish to ascertain the relative mathe 

 matical values of different pleasures. There is discrimi 

 nation, no doubt, though it is not nearly so fine and so 

 certain as in the case of simple ideas, such as those of musical 

 pitch or colour, but there is no measurement. 



For purposes of mere discrimination, pleasures may be 

 graduated in two series, that is to say, either by their inten 

 sity or by their duration, and it is necessary to consider 

 each series separately with reference to its ethical values. 



It is possible that the feeling of intensity in pleasure 

 may be analogous to the feeling of extensity which supplies 

 the foundation of our ideas in space ; but pleasures them 

 selves are never in space, they can never be exactly located 

 or described in terms of spatial dimensions. We cannot 

 say whether the pleasure of listening to good music is 

 in the heart or in the head , and we are quite unable to 

 estimate it by yards or gallons. Direct spatial measure 

 ments are therefore out of the question. But we have seen 

 that other intensities, such as the depth of blue in the sky, 

 can be measured indirectly if a rhythm in time or space can 

 be discovered which varies exactly with the variations of 

 intensity. Such a rhythm for the measurement of intensities 

 of pleasure and pain may conceivably be discovered in the 

 organic processes of the body. But this discovery has not 

 yet been made, and it is safe to say that, in the present 





