PLAY AND INSTINCT. 31 



ade when we again stand at a turning point of time, 

 when in polite literature the word is, Naturalism is 

 dead; when plastic art turns toward a manifold, mys- 

 tic, new idealism; when a Neo-vitalism is arising in bi- 

 ology; when a Brunetiere proclaims with cool audacity 

 the bankruptcy of positive science * — such a time is 

 hardly a suitable one for the too confident assertion of 

 the all-sufficiency of the exact sciences. Weismann has 

 indeed given the title " The All-sufficiency of Natural 

 Selection " to one of his essays, but in another of his 

 writings occurs a figure which I like better. In con- 

 trast to the common opinion which likens empirical 

 knowledge to a building resting on sure foundations 

 and rising from a firm basement safely to the high- 

 est story, he says of the exact sciences : " They all 

 build from above, and not one of them has found a 

 basement yet — not even physics." f This is indeed 

 true. The metaphysical problems do not float above 

 us far off in the clouds while we peacefully do our 

 work on the firm, enduring earth, but they are rather 

 beneath us, and our clear empirical knowledge rests 

 on their mysterious depths like the sun-reflected sails 

 of a ship on dark waves. So long as this is so, man 

 can not satisfy himself with the " unknowable " and 

 the " ignorabimus " of positivism, but will constantly 

 seek to fathom these bafflingly mysterious depths on 

 which he is borne along. In this book, however, no 

 attempt is made at a metaphysical solution of instinct 



them to the three stages of individual development — childhood, 

 youth, and manhood. Cours de philosophic positive, second edi- 

 tion, 1852, vol. i, pp. 14, 17. 



* F. Brunetiere, La science et la religion, Paris, 1895. 



f Die Bedeutung der sexuellen Fortpflanzung fur die Selec- 

 tionstheorie, Jena, 1886, p. 66. 



