GROUNDS FOR HOPE AND PATIENCE. 315 



It is this reflection which must always teach humility to 

 the scientific student, even while he rejoices in the achieve- 

 ments of human patience and genius. He will not despair 

 for he knows that great victories have been won: he will 

 not grow arrogant, for he knows that he is still on the 

 threshold of eternal truth. As Sir J. Herschel has justly 

 said : " He who has seen obscurities, which appeared im- 

 penetrable, in physical and mathematical science, suddenly 

 dispelled, and the most barren and unpromising fields of 

 inquiry converted, as if by inspiration, into rich and inex- 

 haustible springs of knowledge and power, on a simple 

 change of our point of view, or by merely bringing them 

 to bear on some principle which it never occurred before 

 to try, will surely be the very last to acquiesce in any dispirit- 

 ing prospects of either the present or the future destinies of 

 mankind; while, on the other hand, the boundless views of 

 intellectual and moral, as well as material relations, which 

 open to him on all hands in the course of these pursuits, 

 the knowledge of the trivial place he occupies in the scale 

 of creation, and the sense continually pressed upon him of 

 his own weakness and incapacity to suspend or modify the 

 slightest movement of the vast machinery he sees in action 

 around him, must effectually convince him that humility of 

 pretension, no less than confidence of hope, is what best 

 becomes his character."* 



The temperature of the terrestrial surface perpetually varies 



* Sir J. Herschel, " Preliminary Discourse on the Study of Natural 

 Philosophy." 



