2 30 PHYSICAL SCIENCE BK. vi 



say, will be the reward of our labour ? That 

 reward, I say, which surpasses all others, the 

 3 knowledge of nature. Among the many serviceable 

 lessons to be derived from such researches, no 

 feature is more commendable than this, that man is 

 thereby made to dwell upon the sight of his own 

 grandeur 1 ; the study is pursued, not in hope of gain, 

 but from the wonder it excites. Let us inquire, there- 

 fore, what it is that brings about all this. The 

 inquiry is so fascinating to me that although long 

 ago in my youth I published a volume on earth- 

 quakes, I am anxious to make another trial of my 

 powers, and to see whether age has added anything 

 to my knowledge, or, at any rate, to my industry. 



1 THE cause of earthquakes has been assigned 

 variously by different authorities to water, fire, air, 

 and to the earth itself ; some assign it to a combina- 

 tion of several of the causes, others, to a union of them 

 all. Certain writers have stated that it was plain 

 to them that some one of these causes produced the 

 earthquake, but it was not plain which. Let us 

 look at the various opinions in detail. First of 

 all, I feel bound to say in general terms that the 

 old views are crude and inexact. As yet men 

 were groping their way round truth. Everything 

 was new to those who made the first attempt to 

 grasp it ; only later were the subjects accurately 

 investigated. But all subsequent discoveries must 

 nonetheless be set down to the credit of those early 



2 thinkers. It was a task demanding great courage 



1 The meaning may rather be the grandeur of the subject. 



