256 THE LIMITATIONS OF SCIENCE 



the only two examples which have been worked out 

 in America are the Jukes and the Edwards families. 

 The first has shown itself to be an undesirable and 

 the other a desirable strain. But curiously enough the 

 first ancestress in America of each of these families 

 was not a moral woman. It is sufficiently easy to look 

 back and decide what characteristics proved to be un- 

 desirable, but it is a very different thing to look for- 

 ward and determine who should establish a family 

 and who should not. Not even the most enthusiastic 

 eugenists can hope to unravel the genealogies of more 

 than a small proportion of families. And it would 

 require accurate genealogies of many families, not 

 only of successive generations but also of the char- 

 acteristics of its members, to settle whether a strain 

 of immorality came simply from an excess of vitality 

 or was the result of degeneracy. 



If eugenics is a problem too complex for solution, 

 its companion, euthenics, is an example of trying to 

 assign to science a problem it has no means of solving. 

 Science knows no method of constraining an indi- 

 vidual to conduct himself so as to further the exist- 

 ence of a perfect race. The greatest difficulty in all 

 ethical systems is to provide an efficient check on the 

 passions. The strongest check is evidently the belief 

 that disaster to himself will result from disobedience 

 of the laws of right conduct. And yet the man is rare 

 who can by his will refrain from those habits and 



