TIME AND CHANGE 
entiated and their complex water-systems estab- 
lished till well into Tertiary times — in short, that 
they have passed more and more from the simple 
to the complex, from the disorganized to the organ- 
ized. When man comes to draw his sustenance 
from their breasts, may they not be said to have 
reached the mammalian stage ? 
The fertile plain and valley and the rounded hill 
are of slow growth, immensely slow. But any given 
stage of the earth has followed naturally from the 
previous stage, only more and more and higher and 
higher forces took a hand in the game. First its ele- 
ments passed through the stage of fire, then through 
the stage of water, then merged into the stage of air. 
More and more the aerial elements — oxygen, car- 
bon, nitrogen — have entered into its constituents 
and fattened the soil. The humanizing of the earth 
has been largely a process of oxidation. More than 
disintegrated rock makes up the soil; the air and the 
rains and the snows have all contributed a share. 
The history of the soil which we turn with our 
spade, and stamp with our shoes, covers millions 
upon millions of years. It is the ashes of the moun- 
tains, the leavings of untold generations of animal 
and vegetable life. It came out of the sea, it drifted 
from the heavens; it flowed out from the fiery heart 
of the globe; it has been worked over and over by 
frost and flood, blown by winds, shoveled by ice, 
— mixed and kneaded and moulded as the house- 
14 
