ck, we shall suppose a continent composed
of either dry sand or watery mud, without solidity or stability, how
imperfect still would be that world for the purpose of sustaining lofty
trees and affording fruitful soils!

We have now mentioned the two extreme states of things; but the
constitution of this earth is no other than an indefinite number of
soils and situations, placed between those two extremes, and graduating
from the one extreme, in which some species of animals and plants
delight in finding their prosperity, to the other, in which another
species, which would perish in the first, are made to grow luxuriantly.
That is to say, the surface of this earth, which is so widely adapted to
the purpose of an extensive system of vegetating bodies and breathing
animals, must consist of a gradation from solid rock to tender earth,
from watery soil to dry situations; all this is requisite, and nothing
short of this can fulfil the purpose of that world which we actually
see.

We have been representing this continent of our earth as coming out of
the ocean a solid mass, which surely it is in general, or in a great
degree; but we find the surface of this body at present in a very
different state; and now it will be proper to take a view of this change
from solid rock to fertile soil.

Upon this occasion I shall give the description of nature from the
writings of a philosopher who has particularly studied this subject. It
is true that M. de Luc, who furnishes the description, draws, from this
process of nature, an argument for the perpetual duration or stability
of mountains; and this is the very opposite of that view which I have
taken of the subject; but as, in this operation of nature producing
plants on stones, he allows the surface of the solid stone to be changed
into earth and vegetables, it is indifferent to the present theory how
he shall employ this earth and vegetable substance, provided it be
acknowledged that there is a change from the solid state of rock to the
loose or tender nature of an earth, from the state of a body immovable
by the floods and impenetrable to the roots of plants, to one in which
some part of the body may be penetrated and removed.

[8]"Les pluies et les rosees forment partout ou elles sejournent, des
depots qui sont la premiere source de toute _vegetation_. Ces depots
sont toujours meles des semences des _mousses_, que l'air charie
continuellement, et auxquelles se joignent bientot les