FOREST TREES AND FOREST SCENERY 
the last rays of the sun, obscures the 
contours of the forests and makes 
them even more sublime. This, too, 
were not possible without great mass 
and uniformity of aspect. 
The interchange between lights and 
shadows cast by the moving clouds is 
nowhere so effectively exhibited as in 
higher altitudes and over the surfaces of 
evergreen forests. A wide expanse en- 
ables us to follow with our eyes the in- 
teresting chase of the cloud shadows, as 
they fly up the slopes, the steeper the 
faster, and glide noiselessly but swiftly 
over outstretched areas of endless green. 
The clouds seem to move faster over 
mountain ranges, as a rule, than they 
do over the low valleys. Or is it only 
because now we see them nearer by and 
can gage the rapidity of their flight? 
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