constant in type, distribution, and proportion, and the physical
geography of the earth would have remained undisturbed for indefinite
periods, and been subject to revolution only from slow development, from
possible, unknown cosmical causes, or from geological action.

But man, the domestic animals that serve him, the field and garden
plants the products of which supply him with food and clothing, cannot
subsist and rise to the full development of their higher properties,
unless brute and unconscious nature be effectually combated, and, in a
great degree, vanquished by human art. Hence, a certain measure of
transformation of terrestrial surface, of suppression of natural, and
stimulation of artificially modified productivity becomes necessary.
This measure man has unfortunately exceeded. He has felled the forests
whose network of fibrous roots bound the mould to the rocky skeleton of
the earth; but had he allowed here and there a belt of woodland to
reproduce itself by spontaneous propagation, most of the mischiefs which
his reckless destruction of the natural protection of the soil has
occasioned would have been averted. He has broken up the mountain
reservoirs, the percolation of whose waters through unseen channels
supplied the fountains that refreshed his cattle and fertilized his
fields; but he has neglected to maintain the cisterns and the canals of
irrigation which a wise antiquity had constructed to neutralize the
consequences of its own imprudence. While he has torn the thin glebe
which confined the light earth of extensive plains, and has destroyed
the fringe of semi-aquatic plants which skirted the coast and checked
the drifting of the sea sand, he has failed to prevent the spreading of
the dunes by clothing them with artificially propagated vegetation. He
has ruthlessly warred on all the tribes of animated nature whose spoil
he could convert to his own uses, and he has not protected the birds
which prey on the insects most destructive to his own harvests.