IN THE LAST HALF-CENTUEY. 89 



from the days of the Ionian school on- 

 wards, the view that the universe was the 

 result of such a process should have 

 maintained itself as a leading dogma 

 of philosophy. The emanistic theories 

 which played so great a part in ISTeopla- 

 tonic philosophy and Gfnostic theology are 

 forms of evolution. In the seventeenth 

 century, Descartes propounded a scheme 

 of evolution, as an hypothesis of what 

 might have been the mode of origin of the 

 world, while professing to accept the ec- 

 clesiastical scheme of creation, as an ac- 

 count of that which actually was its man- 

 ner of coming into existence. In the 

 eighteenth century, Kant put forth a re- 

 markable speculation as to the origin of 

 the solar system, closely similar to that 

 subsequently adopted by Laplace and 

 destined to become famous under the title 

 of the 'nebular hypothesis.' 



The careful observations and the acute 

 reasonings of the Italian geologists of the 



