Uniformity in Geological Change 



though now existing, are veiled from sight. 

 Rocks, also, produced by subterranean fire in 

 former ages, at great depths in the bowels of the 

 earth, present us, when upraised by gradual 

 movements, and exposed to the light of heaven, 

 with an image of those changes which the deep- 

 seated volcano may now occasion in the nether 

 regions. Thus, although we are mere sojourners 

 on the surface of the planet, chained to a mere 

 point in space, enduring but for a moment of 

 time, the human mind is not only enabled to 

 number worlds beyond the unassisted ken of 

 mortal eye, but to trace the events of indefinite 

 ages before the creation of our race, and is not 

 even withheld from penetrating into the dark 

 secrets of the ocean, or the interior of the solid 

 globe; free, like the spirit which Virgil described 

 as animating the universe: 



ire per omnes 



Terrasque, tractusque maris, cr*?lumque profundum. 



[ moving through all lands, and spaces of the sea 



and the depth of heaven.Q 



137 



