126 PHYSICAL SCIENCE BK. m 



river course can drain dry. The exact explanation 

 of its reserve strength has not yet been discovered. 

 It is only the superfluous portion of it that is 



2 released. Now, there are some of these beliefs 

 to which we may safely subscribe ; but I hold this 

 further opinion. My firm conviction is that the 

 earth is organised by nature much after the plan of 

 our bodies, in which there are both veins and arteries, 



3 the former blood-vessels, the latter air-vessels. In 

 the earth likewise there are some routes by which 

 water passes, and some by which air. So exactly 

 alike is the resemblance to our bodies in nature's 

 formation of the earth, that our ancestors have 

 spoken of veins ( = springs) of water. Again, in 

 our bodies there is not merely blood, but many 

 other kinds of moisture, some essential to life, 

 others tainted and somewhat thick brain in the 

 head, marrow in the bones, mucus, saliva, tears, 

 and a kind of lubricating substance that suffuses the 

 joints, and enables them to turn more quickly 

 ( = synovial fluid). 



So, too, in the earth there are several different 



4 kinds of moisture. There are some kinds that 

 grow hard when fully formed. Hence arises all the 

 metalliferous soil, from which our avarice seeks 

 gold and silver. Then there is the kind which 

 turns from liquid into stone. In some localities 

 the earth and its moisture combine to form a 

 liquid like bitumen and other substances of the 

 same kind. There, then, we find the cause of 

 waters produced according to the law and will 



5 of nature. But as in our bodies, so in the earth, 

 humours often contract taints of various kinds. A 

 blow, or some shock, or exhaustion of the ground, 

 or cold or heat injures the natural vigour. A vein 



