THE THEORY OF COURTSHIP 147 



the essentially positive spirit of philosophy and science 

 at the present day. 



Here again, too, the immense logical superiority of 

 Charles Darwin's rigorous and exhaustive inductive 

 method over the loose suggestiveness of his grandfather 

 Erasmus may easily be observed. For while Erasmus 

 merely throws out a clever and interesting hint as to 

 the supposed method and intention of nature, Charles 

 Darwin proves his thesis, point by point, with almost 

 mathematical exactitude, leaving no objection unmet 

 behind him, but giving statistical and inductive warrant 

 for every step in his cumulative argument. He goes 

 carefully into the numerical proportion of the two sexes 

 in various species ; into the relative dates of arrival in 

 any particular country of the males and females of 

 migratory birds ; into the question whether any indivi- 

 duals ever remain in the long run unpaired ; into the 

 chances of the earliest-mated or most vigorous couples 

 leaving behind more numerous or stronger offspring 

 to represent them in the next generation. He collects 

 from every quarter and from all sources whatever 

 available evidence can be obtained as to the courtship 

 and rivalry of birds and butterflies, of deer and ante- 

 lopes, of fish and lizards. He shows by numerous 

 examples and quotations how even flies coquet together 

 in their pretty rhythmical aerial dances; how wasps 

 battle eagerly with one another to secure possession of 

 their unconcerned mates ; how cicadas strive to win 

 their 'voiceless brides' with stridulating music; how 

 sphinx-moths endeavour to allure their partners with 

 the musky odour of their pencilled wings ; and how 

 emperors and orange-tips display their gorgeous spots 



