he
action of general laws. That the rains and rivers, aided by subterranean
forces, had modelled the country, had formed the hills and valleys, had
scooped out the river beds, and levelled the plains;--and it would only
be after much patient observation and study, after having watched the
minute changes produced year by year, and multiplying them by thousands
and ten thousands, after visiting the various regions of the earth and
seeing the changes everywhere going on, and the unmistakable signs of
greater changes in past times,--that he could be made to understand that
the surface of the earth, however beautiful and harmonious it may
appear, is strictly due in every detail to the action of forces which
are demonstrably self-adjusting.

Moreover, when he had sufficiently extended his inquiries, he would
find, that every evil effect which he would imagine must be the result
of non-adjustment does somewhere or other occur, only it is not always
evil. Looking on a fertile valley, he would perhaps say--"If the channel
of this river were not well adjusted, if for a few miles it sloped the
wrong way, the water could not escape, and all this luxuriant valley,
full of human beings, would become a waste of waters." Well, there are
hundreds of such cases. Every lake is a valley "wasted by water," and in
some cases (as the Dead Sea) it is a positive evil, a blot upon the
harmony and adaptation of the surface of the earth. Again, he might
say--"If rain did not fall here, but the clouds passed over us to some
other regions, this verdant and highly cultivated plain would become a
desert." And there are such deserts over a large part of the earth,
which abundant rains would convert into pleasant dwelling-places for
man. Or he might observe some great navigable river, and reflect how
easily rocks, or a steeper channel in places, might render it useless to
man;--and a little inquiry would show him hundreds of rivers in every
part of the world, which are thus rendered useless for navigation.

Exactly the same thing occurs in organic nature. We see some one
wonderful case of adjustment, some unusual development of an organ, but
we pass over the hundreds of cases in which that adjustment and
development do not occur. No doubt when one adjustment is absent another
takes its place, because no organism can continue to exist that is not
adjusted to its environment; and unceasing variation with unlimited
powers of multiplication, in most cases,