“Quelle richesse dans les ressources de la nature!  La pesanteur n’est pas plus prete a entrainer les pierres qui se detachent des montagnes, que l’air a fournir de semences celles qui se fixent:  et des qu’une fois elles sont recouvertes de plantes, elles sont certainement fixees pour toujours, du moins contre les injures de l’air.  Le fait meme nous l’annonce.  Si ces ravins ou ces terreins quelconques, tendoient encore a rouler ou a se degrader, en un mot a se detruire de quelque maniere que ce fut, ils ne le recouvriroient, ni de mousses ni d’aucune autre plante.  La premiere vegetation est due a quelque depot de terre vegetable; et les pluies ou l’air n’en forment que lentement; le moindre mouvement la detruite.  Le terrein est donc bien certainement fixe quand il se recouvre de plantes; et s’il s’y accumule de la terre vegetable, c’est un signe bien evident que rien ne l’attaque plus:  car elle seroit la premiere emportee si quelque cause exterieure tendoit a detruire le sol qui la porte.”

The doctrine here laid down by our author consists in this; first, That there is a genus of plants calculated to grow upon rocks or stones; those hard bodies then decay, in decomposing themselves, and affording sustenance to the plants which they sustain.  Secondly, That by this dissolution of those rocks, and the accumulation of those vegetable bodies, there is soil prepared for the nurture and propagation of another genus of plants, by which the surface of the earth, naturally barren, is to be fertilised.  It is also in this natural progress of things that the solid parts of the globe come to be wasted in the operations of the surface, and that lofty rocks are levelled, in always tending to bring the uneven surface of the earth to a slope of vegetating or fertile soil.

Here we are to distinguish carefully between the facts described by this author, who has seen so much of nature, and the conclusion which he would draw from his principles.  The surface of most stones are dissolved, or corroded by the air and moisture.  This gives lodgement to the roots of plants, which grow, die, and decay; and these are carried away with the earthy parts of the solid stone, in order to form a vegetable soil for larger plants, growing upon some bottom or resting place to which that earth is carried.  Here is so far the purpose of rocks, to sustain a genus of plants which are contrived to live upon that soil; and here is so far a purpose for certain plants, in decomposing rocks to form a soil for other plants which have been made upon a larger scale, and are adapted to the use of man, the ultimate in the view of nature.

Our author concludes thus:  (p. 37.) “Le tems ne fera qu’augmenter l’epaisseur de la couche de terre vegetable qui couvre les montagnes, et qui les garantit ainsi de plus en plus de cette destruction a laquelle on les croit exposes:  les pluies en un mot, au lieu de les degrader comme on se l’imagine y accumuleront leurs depots.  Tel est l’agent simple qu’employe si admirablement le Createur pour la conservation de son ouvrage.”