PROGRESSIVENESS OF SCIENCE. 45 



the progress of the sciences within a century, and 

 there are many ways in which the impression of 

 progressiveness may be made vivid. Many of the 

 articles in the older Encyclopaedias are splendid 

 pieces of intellectual workmanship, but to read one 

 of them and then its correspondent in a modern 

 encyclopaedia is like a sudden transition from an 

 incipient spring to midsummer. And yet we know 

 that, to our successors, this modern article will soon 

 seem quite vernal. 



There have been scientific works like those of 

 Aristotle, Pliny, and Galen which lasted in varied 

 forms through centuries ; and there are masterpieces, 

 like the books of Euclid, and Newton's Principia, 

 which in some form will be text-books while learning 

 lasts; but every one knows that nowadays even the 

 best of text-books is very short-lived. 



If we take a survey of the sciences, from astron- 

 omy to sociology, how striking are the changes, alike 

 as to facts and ideas, in the last hundred years. He 

 must be indeed blase or callous who does not feel ex- 

 hilaration in the thought of the advance in the in- 

 terval between Laplace and Lockyer ; between Count 

 Rumford and Lord Kelvin; between Hutton and 

 Playfair and the Geikies; between Richard Owen 

 and Louis Agassiz on the one hand, Cope and Zittel 

 on the other; between Cuvier and Huxley; between 

 Lamarck and Ray Lankester ; between Von Baer and 

 Francis Balfour; between Bichat and Sir Michael 

 Foster; between Erasmus Darwin and his grand- 

 son ; between Reimarus and Romanes ; between Prich- 

 ard and Taylor; between Adam Smith and Herbert 

 Spencer. To any one who knows even a little con- 

 cerning the history of science the contrasts of these 

 coupled names must stimulate afresh the impression 



