this case, the reasoning of this philosopher is to be
justified, so far as he proceeded upon principles which could not lead
him to the truth, his conduct is not so irreproachable in applying them
to cases by which their fallacy might have been detected. This author
acknowledges calcareous strata to be aquiform in their original; but,
in those mountains which he has so much examined, he will find those
aquiform bodies have undergone the same species of changes, which made
him conclude that those schistus mountains had not been truly aquiform,
as he at first had thought them. This would have led him to reason back
upon his principles, and to say, _If one species of strata may be thus
changed in its texture, and its shape, may not another be equally so?
Therefore, may not the origin of both be similar_?

But least I should do injustice to this author, to whom we are indebted
for many valuable observations in natural history, I shall transcribe
what he has said upon the subject, being persuaded that my readers will
not think this improper in me, or impertinent to the argument.

"Quand nous fumes une fois persuades que la mer n'avoit pas fait
toutes les _montagnes_, nous entreprimes de decouvrir les caracteres
distinctifs de celles qui lui devoient leur origine; et s'il etoit, par
exemple, des matieres qui leur fussent propres. Mais nous y trouvames
les memes difficultes qu'on rencontre dans tout ce qu'on veut classer
dans la nature. On peut bien distinguer entr'elles les choses qui
ont fortement l'empreinte de leur classe; mais les confins echappent
toujours.

"C'est la, pour le dire en passant, ce qui a pu conduire quelques
philosophes a imaginer cette _chaine des etres_ ou ils supposent,
que, de la pierre a l'homme et plus haut, les nuances sont reellement
imperceptibles. Comme si, quoique les limites soyent cachees a nos sens,
notre intelligence ne nous disoit pas, qu'il y a un _saut_, une distance
meme infinie, entre le plus petit degre d'organization _propageante_,
et la matiere unie par la simple cohesion: entre le plus petit degre de
_sensibilite_, et la matiere insensible: entre la plus petite capacite
d'observer et de transmettre ses observations, et l'instinct constamment
le meme dans l'espece. Toutes ces differences tranchees existent dans la
nature; mais notre incapacite de rien connoitre a fond, et la necessite
ou nous sommes de juger de tout sur des apparences, nous fait perdre
presque toutes les limites,