The description of those natural operations, which M. de Luc has given with a view to establish the duration of the mountains, is founded upon nothing but their destruction. These beds of rivers, which, according to our author, are hardly to be wasted any more, will not satisfy a philosopher, who requires to see no degree of wasting in a body which is to remain for ever, or continue without change. But, however untenable this supposition of a fixed state in the surface of this earth, the accuracy of the natural philosopher may still be observed in the absurdity of the proposition. «L'état des montagnes sera fixe, partout où les rivières seront arrivées au point de n'emporter pas plus de limon hors de leur enceinte, que l'air et les pluies n'y déposeront de terre végétable, et voila enfin quel sera le repos, l'état permanent de la surface de notre globe. Car alors il y aura compensation entre les destructions et les réparations simultanées, et les montagnes sûrement ne s'abaisseront plus.»
Surely, if there is in the system of nature wisdom, we may look for compensation between the destroying and repairing operations of the globe. But why seek for this compensation in the rest or immobility of things? Why suppose perfection in the want of change? The summit of the Alps was once the bottom of the sea; the existence of our land depended then upon the change of seas and continents. But has the earth already undergone so great changes, and is it not yet arrived at the period of its perfection? How can a philosopher, who is so much employed in contemplating the beauty of nature, the wisdom and goodness of Providence, allow himself to entertain such mean ideas of the system as to suppose, that, in the indefinite succession of time past, there has not been perfection in the works of nature? Every material being exists in motion, every immaterial being in action and in passion; rest exists not any where; nor is it found in any other way, except among the parts of space. Surely it is contrary to every species of philosophy, whether ancient or modern, to found a system on the inutility of repose, or place perfection in the vacuity of rest, when every thing that truly exists, exists in motion; when every real information which we have is derived from a change; and when every excess in nature is compensated, not by rest, but by alternation.
M. de Luc allows the rivers to carry matter always to the sea; but then, at a certain period, this matter carried by the floods is to be compensated to the mountains by the vegetable earth received from the air and rains. Here is a proposition which should be well considered, before it be admitted as a principle, which shall establish the perpetuity of these mountains, if it be true; or, if false, assure us of their future demolition. Let us now examine it.
If from air and rain there is produced earth which cannot afterwards be resolved by the operation of those elements, and thus again dissolved in the air and water of the land, then this author might have had some pretext, however insufficient, for alledging that it might be possible to compensate the loss of mineral substances, carried off the surface of the earth, by the production of this vegetable matter from the air and rain; but, when there is not sufficient reason to conclude that any substance, produced in vegetation, can resist the continued influences of the air and water, without being decomposed in its principles, and at last entirely dissolved in water, the cautious argument here employed by this author, for the permanency of mountains, must appear as groundless in its principle as it would be insufficient for his purpose, were it to be admitted; but this will require some discussion.
That which preserves vegetable bodies so long from dissolution in water, is what may be called the inflammable or phlogistic composition of those bodies. This composition is quickly resolved in combustion; but it is no less surely resolved by the influences of the sun and atmosphere, only in a slower manner. Therefore, to place the permanency of this earth, or any of its surface, upon a substance which in that situation necessarily decays, is to form a speculation inconsistent with the principles of natural philosophy[11].
Footnote 11:[ (return) ] It is from inadvertency to this fact in natural history, the consuming of vegetable substances exposed to the influences of the atmosphere, that M. de Luc, in his Histoire de la Terre, has pretended to determine the past duration of the German heaths as not of a very high antiquity. He has measured the increase of the vegetable soil, an increase formed by the accumulation of the decayed heath; and, from the annual increase or deposits of vegetable matter on that surface, he has formed a calculation which he then applies to every period of this turfy augmentation, not considering that there may be definitive causes which increase with this growing soil, and which, increasing at a greater rate in proportion as the soil augments, may set a period to the further augmentation of that vegetable soil. Such is fire in the burning of those parched heaths; such is the slower but constant and growing operation of the oxygenating atmosphere upon this turfy substance exposed to the air and moisture. This author has very well described the constant augmentation of this vegetable substance in the morasses of that country, as it also happens in those of our own; but there is a wide difference in those two cases of peat bog and healthy turf; the vegetable substance in the morass is under water, and therefore has its inflammable quality or combustible substance protected from the consuming operation of the vital or atmospheric air; the turfy soil, on the contrary, is exposed to this source of resolution in the other situation.
But even supposing that the degradation of mountains were to be suspended by the pretended compensation which is formed, by the rivers carrying mineral mud into the sea, and the air and rain producing vegetable earth; in what must this operation end? In carrying into the sea, to be deposited at its bottom, all the vegetable earth produced by the air and rain. But our cosmologist, in thus procuring an eternal station to his mountains, has not told us whether this transmutation of the air and rain be a finite operation, or one that is infinite; whether it be in other respects confident with the natural operations of the globe; and whether, to have the air and water of the globe converted into earth, would ultimately promote, or not, that perfection which he wishes to establish. Here, therefore, in allowing to this philosophy all its suppositions, it would be necessary to make another compensation, in preserving mountains at the expense of air and rain; and, the waste of air and water, which are limited, would require to be repaired.
It is not in our purpose here to treat of moral causes; but this author having endeavoured to fortify his system by observing, that the world certainly cannot be ancient, since men have not ceased as yet to quarrel and fight, (Lettre 34.) it may be proper to observe, that the absolute rest of land, like the peace among mankind, will never happen till those things are changed in their nature and constitution, that is to say, until the matter of this globe shall be no more a living world, and man no more an animal that reasons from his proper knowledge, which is still imperfect. If man must learn to reason, as children learn to speak, he must reason erroneously before he reasons right; therefore, philosophers will differ in their opinions as long as there is any thing for man to learn. But this is right; for, how are false opinions to be corrected, except in being opposed by the opinions of other men? It is foolish, indeed, for men to quarrel and fight, because they differ in opinion. Man quarrels properly, when he is angry; and anger perhaps is almost always ultimately founded upon erroneous opinion. But, in nature, there is no opinion; there is truth in every thing that is in nature; and in man alone is error. Let us, therefore, in studying nature, learn to know the truth, and not indulge erroneous notions, by endeavouring to correct, in nature, that which perhaps is only wrong in our opinion.
Having shown that every thing, which is moveable upon the surface of the land, tends to the sea, however slowly in its pace, we are now to examine, what comes of those materials deposited within the regions of the waves, still however within the reach of man, and still subservient more immediately to that soil on which plants grow, and man may dwell.
As, from the summit of the land, the natural tendency of moveable bodies is to fall into the water of the sea, so, from the borders of the land or coast, there being a declivity towards the deepest bottom of the sea, and there being currents in the waters of the ocean occasionally rendered more rapid on the shore, every moveable thing must tend to travel from the coast, and to proceed alone; the shelving bottom of the sea into the unfathomable deep, when they are beyond the reach of man or the possibility of returning to the shore.