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nect this fact with the phenomena already known, " and has therefore been justly abandoned. In this

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manner, they say, have passed away the theories of Woodward, Burnet, Whiston, and even of Buffon; " and so will pass, in their turn, those of Hutton and "Werner." He does not add that of De Luc, but others have done so upon the same grounds.

15. Some valuable remarks are contained in the arguments which Mr. Playfair adduces in opposition to this prejudice, and motives for hope are suggested by him, which indicate great penetration: I shall therefore again use his own words for expressing these motives. But, among the means which he points out to ensure success, I shall notice one, as it occurs in the course of the quotation, which will hereafter become an important subject of discussion.

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"This unfavourable view of geology," he conti ought not, however, to be received without examination; in science, presumption is less hurt"ful than despair, and inactivity is more dangerous "than error. One reason of the rapid succession "of geological theories, is the mistake that has been "made as to their object, and the folly of attempting

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to explain by them the first origin of things. This "mistake has led to fanciful speculations, that had nothing but their novelty to recommend them, and which, when that charm had ceased, were rejected as mere suppositions, incapable of proof. But if "it is once settled that a theory of the earth ought "to have no other aim than to discover the laws that " regulate

"regulate the changes on the surface, or in the in"terior of the globe, the subject is brought within "the sphere either of observation, or analogy; and "there is no reason to suppose that man, who has "numbered the stars, and measured their forces, "shall ultimately prove unequal to this investiga❝tion."

16. This is the means of success, in regard to which I differ from Mr. Playfair: he would lay down, as a fixed point in geology, the very part of his friend's theory, to which is probably owing the little attention which has, as he complains, been paid to it; namely, that nothing is to be the object of investigation in the history of the earth, but the laws that regulate the changes of its surface; excluding thus every inquiry respecting a primordial constitution of the earth, whence these changes might follow. It is not from its obscurity, as Mr. Playfair imagines, that his friend's theory has not attracted much attention, since it is not difficult to be understood; but its nature, which I shall hereafter discuss. I shall at present, therefore, confine myself to noticing a mistake, which he has himself committed in respect to other theorics. I am acquainted with no geological system worthy of regard, attempting to explain the first origin of things, which in truth would be a folly. But, by tracing with the necessary attention the characters of geological monuments, a succession is clearly discernible, by means of which I believe it possible to go back to some epoch, at which none of them did as yet exist, and to determine what was then the state

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of things upon our globe, and what are the causes from which its actual state has proceeded. For the present, I shall content myself with thus noticing those objects of discussion, of which hereafter I shall treat at large; and I now return to the arguments of Mr. Playfair against scepticism in geology, in which we fully agree.

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"Again," he says, "theories that have a rational object, though they be false or imperfect in their principles, are for the most part approximations to the truth, suited to the information at the "time when they were proposed. They are steps, therefore, in the advancement of knowledge, and are terms of a series that must end when the real "laws of nature are discovered. It is, on this "account, rash to conclude, that, in the revolutions of science, what has happened must continue to happen, and because systems have changed rapidly "in time past, that they must necessarily do so in "time to come.

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"He who would have reasoned so, and who had seen the ancient physical systems, at first all rivals to one another, and then swallowed up by the Aristotelian; the Aristotelian physics giving way to those of Des Cartes, and the physics of Des "Cartes to those of Newton; would have predicted "that these last were also, in their turn, to give

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place to the philosophy of some later period. "This is, however, a conclusion that hardly any one "will now be bold enough to maintain, after a hun

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"dred years of the most scrupulous examination "have done nothing but add to the evidence of the "Newtonian system. It seems certain, therefore, "that the rise and fall of theories in times past, does not argue that the same will happen in the time "that is to come.

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"The multifarious and extremely diversified object of geological researches does, no doubt, ren"der the first steps difficult, and may very well account for the instability hitherto observed in "such theories; but the very same thing gives rea

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son for expecting a very high degree of certainty "to be ultimately attained in these inquiries.

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"Where the phenomena are few and simple, there

may be several different theories that will explain "them in a manner equally satisfactory; and in "such cases, the true and the false hypotheses are "not easily distinguished from one another. When,

on the other hand, the phenomena are greatly "varied, the probability is, that among them some "of those instantia crucis," (phenomena described by Bacon)" will be found, that exclude every hypo"thesis but one, and reduce the explanation given "to the highest degree of certainty.-Hence the "number, the variety, and even the complication of "facts, contribute ultimately to separate truth from "falsehood; and the same causes, which, in any

case, render the first attempts toward a theory "difficult, make the final success of such attempts just so much the more probable."

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17. This new passage of Mr. Playfair convinced me of what I have already stated, that he had formed a very correct judgment of geology; and that, while he had seen the extent of the objects which it ought to comprise, he had not given way to the opinion that it exceeded the reach of human capacity. This passage, as well as many other parts of his work, make it evident that he has carefully studied the immortal Bacon, whose luminous principles are fallen at this day into so much neglect, to the great detriment of natural science. Mr. Playfair well understood that the voluminous writings of that great philosopher had not, for their ultimate object, what superficial naturalists would esteem as solely useful; namely, details of natural history and natural philosophy, to which such persons exclusively attend. Thus, judging Bacon in this single view, they consider themselves as much more cnlightened than he was, although so eminent in his time; and suffer his volumes to remain upon the dusty shelves of libraries, without having perceived in them that, which will ever bring them to the recollection of true philosophers, and which Mr. Playfair has in many respects well understood, though he has sometimes departed from it.

18. The sagacity of Bacon enabled him to discover the immense variety of the phenomena of nature; the strength of his genius, however, prevented him from considering this variety as forming insuperable obstacles to the advancement of science, provided they were studied with less of the impatience and presumption, which, till then, had prevailed among philosophers.

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