125. On what is now said is grounded another objection to Dr Hutton's theory, namely, that the high antiquity ascribed by it to the earth, is inconsistent with that system of chronology which rests on the authority of the Sacred Writings. This objection would no doubt be of weight, if the high antiquity in question were not restricted merely to the globe of the earth, but were also extended to the human race. That the origin of mankind does not go back beyond six or seven thousand years, is a position so involved in the narrative of the Mosaic books, that any thing inconsistent with it, would no doubt stand in opposition to the testimony of those ancient records. On this subject, however, geology is silent; and the history of arts and sciences, when traced as high as any authentic monuments extend, refers the beginnings of civilization to a date not very different from that which has just been mentioned, and infinitely within the limits of the most recent of the epoch as, marked by the physical revolutions of the globe.
On the other hand, the authority of the Sacred Books seems to be but little interested in what regards the mere antiquity of the earth itself; nor does it appear that their language is to be understood literally concerning the age of that body, any more than concerning its figure or its motion. The theory of Dr Hutton stands here precisely on the same footing with the system of Copernicus; for there is no reason to suppose, that it was the purpose of revelation to furnish a standard of geological, any more than of astronomical science. It is admitted, on all hands, that the Scriptures are not intended to resolve physical questions, or to explain matters in no way related to the morality of human actions; and if, in consequence of this principle, a considerable latitude of interpretation were not allowed, we should continue at this moment to believe, that the earth is flat; that the sun moves round the earth; and that the circumference of a circle is no more than three times its diameter.
It is but reasonable, therefore, that we should extend to the geologist the same liberty of speculation, which the astronomer and mathematician are already in possession of; and this may be done, by supposing that the chronology of Moses relates only to the human race. This liberty is not more necessary to Dr Hutton than to other theorists. No ingenuity has been able to reconcile the natural history of the globe with the opinion of its recent origin; and accordingly the cosmologies of Kirwan and De Luc, though contrived with more mineralogical skill, are not less forced and unsatisfactory than those of Burnet and Whiston.
126. It is impossible to look back on the system which we have thus endeavoured to illustrate, without being struck with the novelty and beauty of the views which it sets before us. The very plan and scope of it distinguish it from all other theories of the earth, and point it out as a work of great and original invention. The sole object of such theories has hitherto been, to explain the manner in which the present laws of the mineral kingdom were first established, or began to exist, without treating of the manner in which they now proceed, and by which their continuance is provided for. The authors of these theories have accordingly gone back to a state of things altogether unlike the present, and have confined their reasonings, or their fictions, to a crisis which never has existed but once, and which never can return. Dr Hutton, on the other hand, has guided his investigation by the philosophical maxim, Causam naturalem et assiduam quærimus, non raram et fortuitam. His theory, accordingly, presents us with a system of wise and provident economy, where the same instruments are continually employed, and where the decay and renovation of fossils being carried on at the same time in the different regions allotted to them, preserve in the earth the conditions essential for the support of animal and vegetable life. We have been long accustomed to admire that beautiful contrivance in nature, by which the water of the ocean, drawn up in vapour by the atmosphere, imparts, in its descent, fertility to the earth, and becomes the great cause of vegetation and of life; but now we find, that this vapour not only fertilizes, but creates the soil; prepares it from the solid rock, and, after employing it in the great operations of the surface, carries it back into the regions where all its mineral characters are renewed. Thus, the circulation of moisture through the air, is a prime mover, not only in the annual succession of the seasons, but in the great geological cycle, by which the waste and reproduction of entire continents is circumscribed. Perhaps a more striking view than this, of the wisdom that presides over nature, was never presented by any philosophical system, nor a greater addition ever made to our knowledge of final causes. It is an addition which gives consistency to the rest, by proving, that equal foresight is exerted in providing for the whole and for the parts, and that no less a care is taken to maintain the constitution of the earth, than to preserve the tribes of animals and vegetables which dwell on its surface. In a word, it is the peculiar excellence of this theory, that it ascribes to the phenomena of geology an order similar to that which exists in the provinces of nature with which we are best acquainted; that it produces seas and continents, not by accident, but by the operation of regular and uniform causes; that it makes the decay of one part subservient to the restoration of another, and gives stability to the whole, not by perpetuating individuals, but by reproducing them in succession.
127. Again, in the detail of this theory, and the ample induction on which it is founded, we meet with many facts and observations, either entirely new, or hitherto very imperfectly understood. Thus, the veins which proceed from masses of granite, and penetrate the incumbent schistus, had either escaped the observation of former mineralogists, or the importance of the phenomenon had been entirely overlooked. Dr Hutton has described the appearances with great accuracy, and drawn from them the most interesting conclusions. At the junction of the primary and secondary strata, the facts which he has noted had been observed by others; but no one I think had so fully understood the language which they speak, or had so clearly perceived the consequences that necessarily follow from them. He is the first who distinctly pointed out the characters which distinguish whinstone from lava, and who explained the true relation that subsists between these substances. He also discovered the induration of the strata, in contact with veins of whin, and the charring of the coal in their vicinity. His theory also enabled him to determine the affinity of whinstone and granite to one another, and their relation to the other great bodies of the mineral kingdom.
To the observations of the same excellent geologist, we are indebted for the knowledge of the general and important fact, that all the hard substances of the mineral kingdom, when elevated into the atmosphere, have a tendency to decay, and are subject to a disintegration and waste, to which no limit can be set but that of their entire destruction; that no provision is made on the surface for repairing this waste, and that there, no new fossil is produced; that the formation of all the varied scenery which the surface of the earth exhibits, depends on the operation of causes, the momentary exertions of which are familiar to us, though we knew not before the effects which their accumulated action was able to produce. These are facts in the natural history of the earth, the discovery of which is due to Dr Hutton; and, should we lay all further speculation aside, and consider the theory of the earth as a work too great to be attempted by man, we must still regard the phenomena and laws just mentioned, as forming a solid and valuable addition to our knowledge.
128. If we would compare this theory with others, as to the invisible agents which it employs, we must consider, that fire and water are the two powers which all of them must make use of, so that they can differ from one another only by the way in which they combine these powers. In Dr Hutton's system, water is first employed to deposit and arrange, and then fire to consolidate, mineralize, and lastly, to elevate the strata; but with respect to the unstratified or crystallized substances, the action of fire only is recognised. The system having least affinity to this is the Neptunian, which ascribes the formation of all minerals to the action of water alone, and extends this hypothesis even to the unstratified rocks. Here, therefore, the action of fire is entirely excluded; and the Neptunists have certainly made a great sacrifice to the love of truth, or of paradox, in rejecting the assistance of so powerful an auxiliary.[37]
129. In the systems which employ the agency of the latter element, we are to look for a greater resemblance to that of Dr Hutton, though many and great marks of distinction are easily perceived. In the cosmologies, for example, of Leibnitz and Buffon, fire and water are both employed, as well as in this; but they are employed in a reverse order. These philosophers introduce the action of fire first, and then the action of water, which is to invert the order of nature altogether, as the consolidation of the rocks must be posterior to their stratification. Indeed, the theory of Buffon is singularly defective: besides inverting the order of the two great operations of stratification and consolidation, and of course giving no real explanation of the latter, it gives no account of the elevation, or highly inclined position of the strata; it makes no distinction between stratified and unstratified bodies, nor does it offer any but the most unsatisfactory explanation of the inequalities of the earth's surface. This system, therefore, has but a very distant resemblance to the Huttonian theory.[38]