242 PHYSICAL SCIENCE BK. vi 



XIV 



1 THERE are some who think that, while air and no 

 other cause produces earthquake, it operates in a 

 different way from that which Aristotle supposed. 

 Listen to what they say : Our body is irrigated 

 with blood, and with air which courses everywhere 

 along its own routes. We have some compara 

 tively narrow vessels through which they cannot 

 do more than pass ; some wider, in which they 

 accumulate, and from which they are distributed 



2 to the members. So this whole body of the earth 

 at large has passages alike for water, which performs 

 the function of blood, and for wind, which might 

 be called simply the breath of its life. These two 

 encounter each other at some points, at some points 

 they are stationary. While in our bodies good 

 health is enjoyed, the movement of the veins pre 

 serves its rate undisturbed ; but when there is 

 malady the pulse beats more rapidly, the deep 

 breathing and panting betoken laboured, wearied 

 effort. In like manner the earth remains unshaken 



3 while it maintains its natural position. But if any 

 flaw occur in it, there is a shaking, just as of a 

 body suffering from disease ; for the air which 

 flowed through it with regularity is violently 

 smitten, and causes its veins to quiver ; but not, 

 let me add, in the way, described a little above, 1 

 imagined by those who will have it that the earth 

 is a living creature. In that case the earth, just 

 as an animal does, would feel the agitation equally 

 all over. When a fever seizes any of us, it does 



1 There seems a slight lapse of memory here. Cf. pp. 126, 196. 



