12 THOUGHTS ON NATURAL PHILOSOPHY. 



of our planetary system, as well as those of bodies 

 which fall to the surface of the earth. 



n like manner the different partial theories of 

 optics are rigorous consequences of the properties 

 attributed to a fluid called ether, with which we 

 suppose space to be filled, and whose vibrations 

 serve for the propagation of light and heat. 

 /^This work of synthesis has gradually progressed, 

 Wid these last few years have been marked by very 

 successful efforts in this direction. It should be 

 considered as the true object of physical science in 

 general, and the highest generalization will have 

 been attained when it has been demonstrated that 

 all the physical agents which have hitherto been 

 regarded as distinct, are merely transformations of 

 one and the same primordial agent. 



Sir Isaac Newton had not the advantage of all 

 the wealth of scientific data to assist him that we 

 possess to-day, and his genius was therefore all the 

 more remarkable. It is not surprising that, at the 

 period in which he lived, and in the difficult circum- 

 stances in which he worked, he made mistakes; such 

 as, amongst others, of exalting his idea of gravitation 

 too highly and expecting too much therefrom. Not 

 even he could compel Nature to act according to 

 his thoughts she moveth in her own inimitable 

 calculate and write as we will. Our wisdom 



is to learn of her. 







Sir Isaac Newton had his doubts. He at one 

 time thought of endeavouring to account for orbital 

 phenomena by differences of pressure in the ether, 

 but did not publish a theory on the subject. 



