226 . THE STUDY OF ZOOLOGY vii 



And yet surely there is some great difference 

 between the civilisation of the fourth century and 

 that of the nineteenth, and still more between the 

 intellectual habits and tone of thought of that 

 day and this ? 



And what has made this difference ? I answer 

 fearlessly The prodigious development of physi- 

 cal science within the last two centuries. 



Modern civilisation rests upon physical science ; 

 take away her gifts to our own country, and our 

 position among the leading nations of the world 

 is gone to-morrow; for it is physical science only 

 that makes intelligence and moral energy stronger 

 than brute force. 



The whole of modern thought is steeped in 

 science; it has made its way into the works of 

 our best poets, and even the mere man of letters, 

 who affects to ignore and despise science, is un- 

 consciously impregnated with her spirit, and in- 

 debted for his best products to her methods. I 

 believe that the greatest intellectual revolution 

 mankind has yet seen is now slowly taking place 

 by her agency. She is teaching the world that 

 the ultimate court of appeal is observation and 

 experiment, and not authority ; she is teaching it 

 to estimate the value of evidence ; she is creating 

 a firm and living faith in the existence of immut- 

 able moral and physical laws, perfect obedience to 

 which is the highest possible aim of an intelligent 

 being. 



