SCIENTIFIC FAITH 
doubt our eyes; we know the rains did it. But when 
we see the same thing copied in a broad landscape, 
or on the face of a state or a continent, we find it 
hard to believe the evidence of our own senses. The 
scale upon which it is done, and the time involved, 
put it so far beyond the sphere of our experience 
that something in us, probably the practical, every- 
day man, refuses to be convinced. 
The lay mind can hardly have any adequate con- 
ception of the part erosion, the simple weathering 
of the rocks, has played in shaping our landscapes, 
and in preparing the earth for the abode of man. 
The changes in the surface of the land in one’s life- 
time, or even in the historic period, are so slight 
that the tales the geologists tell us are incredible. 
When, during a recent trip through the great 
Southwest, I saw the earth laid open by erosion as 
I had never before dreamed of, especially when I 
visited those halls of the gods, the Grand Cafion 
and Yosemite Valley, I found my capacity to believe 
in the erosive power of water and the weather quite 
overtaxed. It must be true, I said, what the geol- 
ogists tell us, that water and air did all this; but 
while you look and wait, and while generations 
before you have looked and waited, all is as quiet 
and passive as if the slumber of ages wrapped hill 
and vale. Invisible giants have wrought and delved 
here of whom we never catch a glimpse, nor shall we, 
wait and watch we never so long., No sound of their 
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