fact; nobody that
examines the matter will find any reason to doubt; and it would be as
unreasonable for those to doubt who have not examined, as for those who
find no reasonable subject of doubt to disbelieve.

We are now to suppose the great river to have formed the valley and
extensive plain in which the water runs,--a valley corresponding to the
grandeur of the river by which it has been formed. But, as we ascend
this great valley, we find other valleys branching from this main
valley; and, in all those subordinate valleys, we find rivers
corresponding in like manner with the magnitude of the valley. Here,
therefore, is infinitely more than a single river, and a valley
corresponding to the river; here is a _system_ of rivers and of valleys,
things calculated in perfect wisdom, or properly adapted to each other.

Now it is just as easy, by our theory, to explain this system of rivers
and valleys, as it is to understand the single appearance of a river
and a valley. But it is only in this manner that such a complicated
operation, of a series in rivers and their valleys, is to be explained;
and we can neither suppose the land to be formed with this intention by
a supernatural cause, nor imagine any other natural cause so arranging
things, upon the surface of the earth, as to form this perfect system,
which holds of nothing but itself; a system in which is manifested
wisdom, so far as all the parts are properly adapted to each other, and
thus made to answer that intention which is so visible in the economy of
this world.

The direction of the principal valleys of the Alps, or every mountainous
region of the globe, may be considered as proceeding from the centre of
that region to the plain country in which each river is to terminate;
each secondary river with its valley then branches from the primary as
from a stem, consequently runs in a direction perpendicular or inclined
to the other. But the secondary rivers also have their branches; and
subordinate branches still are branched. In thus tracing rivers and
their branchings, we come at last to rivulets that only run in times of
rain, and at other times are dry. It is here I would wish to carry my
reader, in order to be convinced, with his proper observation, of this
great fact,--that the rivers, in general, have hollowed out their
valleys.

The changes of the valley of the main river are but slow, the plain
indeed is wasted in one place, but it is repaired in anoth