If the valley was made for the river by any other natural cause, either we should tell by what means this work had been performed, or all reasoning upon the subject is at an end, and fancy substituted in its place.  If again the river be considered as the means employed by nature in making this valley, then all the solid parts between the bounding mountains must have been removed, and the fertile plains must have been formed by the water depositing those materials which we find in the soil, and which had come originally from the solid mountains.  There is no occasion to enter into any argument to prove this 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.