SPONTANEOUS GENERATION AND EVOLUTION : CONCLUSION 395 



the average of the race through their descendants; they raise the 

 intellectual average only through their own performances, by increas- 

 ing the knowledge and power handed on by tradition from generation 

 to generation. But the raising of the average of mental capacity, 

 which has undoubtedly taken place to a considerable degree from the 

 Australasian aborigines to the civilized peoples of antiquity and 

 of our own day, can only depend on the struggle for existence 

 between individuals and races. 



But if the human mind has been raised to its present level 

 through the same slow process of selection by means of which all 

 evolution has been directed and raised to the height necessary 

 for the ' desired end,' we must see in this a definite indication that 

 even the greatest mind among us can never see beyond the conditions 

 which limit our capacity for existence, and that now and for all time 

 we cannot hope to understand what is supernatural. We can recognize 

 the stars in the heavens, it is true, and after thousands of years 

 of work we have succeeded in determining their distance, their size, 

 and gravity, as well as their movements and the materials of which 

 they are composed, but we have been able to do all this with 

 a thinking power created for the conditions of human existence upon 

 the earth, that is to say, developed by them, just as we do not only 

 grasp with our hands, but may also play the piano with them. 

 But all that involves a higher thinking power that would enable 

 us to recognize the pseudo-ideas of everlastingness and infinity, the 

 limits of causality, in short, all that we do not know but regard 

 as at best a riddle, will always remain sealed to us, because our 

 intelligence did not, and does not, require this power to maintain 

 our capacity for existence. 



I say this in particular to those who imagine they have summed 

 up the whole situation when they admit that much is still lacking 

 to complete knowledge, say, to a true understanding of the powers 

 of Nature or of the Psyche, but who do not feel that in spite of 

 all our very considerably increased knowledge we stand before the 

 world as a whole as before a great riddle. But I say it also to those 

 who fear that the doctrine of evolution will be the ovex'throw of their 

 faith. Let them not forget that truth can only be harmful, and may 

 even be destructive, when we have only half grasped it, or when 

 we try to evade it. If we follow it unafraid, we shall come now 

 and in the future to the conclusion that a limit is set to our knowledge 

 by our own minds, and that beyond this limit begins the region 

 of faith, and this each must fashion for himself as suits his nature. 

 In regard to ultimate things Goethe has given us the true formula, 



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