tself a bed deep into the
rock or ground, it will not, when the rock is hard, cut a wider
channel than it actually needs; so that if the existing river beds,
through ranges of mountains, had in reality been cut by the streams,
they would be found, wherever the rocks are hard, only in the form of
narrow and profound ravines, like the well-known channel of the
Niagara, below the fall; not in that of extended valleys. And the
actual work of true mountain rivers, though often much greater in
proportion to their body of water than that of the Niagara, is quite
insignificant when compared with the area and depth of the valleys
through which they flow; so that, although in many cases it appears
that those larger valleys have been excavated at earlier periods by
more powerful streams, or by the existing stream in a more powerful
condition, still the great fact remains always equally plain, and
equally admirable, that, whatever the nature and duration of the
agencies employed, the earth was so shaped at first as to direct the
currents of its rivers in the manner most healthy and convenient for
man. The valley of the Rhone may have been in great part excavated, in
early times, by torrents a thousand times larger than the Rhone; but
it could not have been excavated at all, unless the mountains had been
thrown at first into two chains, by which the torrents were set to
work in a given direction. And it is easy to conceive how, under any
less beneficent dispositions of their masses of hill, the continents
of the earth might either have been covered with enormous lakes, as
parts of North America actually are covered; or have become
wildernesses of pestiferous marsh; or lifeless plains, upon which the
water would have dried as it fell, leaving them for great part of the
year desert. Such districts do exist, and exist in vastness; the whole
earth is not prepared for the habitation of man; only certain small
portions are prepared for him,--the houses, as it were, of the human
race, from which they are to look abroad upon the rest of the world;
not to wonder or complain that it is not all house, but to be grateful
for the kindness of the admirable building, in the house itself, as
compared with the rest. It would be as absurd to think it an evil that
all the world is not fit for us to inhabit, as to think it an evil
that the globe is no larger than it is. As much as we shall ever need
is evidently assigned to us for our dwelling-place; th