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his mind, seems to have been (what many French critics have considered as a chief source of the charms of the imitative arts) the pride of conquering difficulties: a feature of his character which he had probably in his own eye, when he remarked (not without some degree of conscious vanity), as a peculiarity in the turn or cast of his intellect, that to him "all difficult things were easy, and all easy things difficult." * Hence the disregard manifested in his writings to the simple and obvious conclusions of experience and common sense; and the perpetual effort to unriddle mysteries over which an impenetrable veil is drawn. "Scilicet sublime et erectum ingenium pulchritudinem ac speciem excelsæ magnæque gloriæ vehementius quam caute appetebat." It is to be regretted, that the sequel of this fine eulogy does not equally apply to him. "Mox mitigavit ratio et ætas; retinuitque, quod est difficillimum, et in sapientiâ modum." How happily does this last expression characterize the temperate wisdom of Locke, when contrasted with that towering, but impotent ambition, which, in the Theories of Optimism and of Pre-established Harmony, seemed to realize the fabled revolt of the giants against the sovereignty of the gods!
After all, a similarity may be traced between these two great men in one intellectual weakness common to both; a facility in the admission of facts, stamped sufficiently (as we should now think) by their own intrinsic evidence, with the marks of incredibility. The observation has been often made with respect to Locke; but it would be difficult to find in Locke's writings, any thing so absurd as an account gravely transmitted by Leibnitz to the Abbé de St. Pierre, and by him communicated to the Royal Academy of Sciences at Paris, of a dog who spoke.‡ No person liberally educated could, I believe, be found at present in any Protestant country of Christendom, capable of such credulity. By what causes so extraordinary a revolution in the minds of men has been effected, with
"Sentio paucos esse mei characteris, et omnia facilia mihi difficilia, omnia contra difficilia mihi facilia esse."-Leib. Op. Tom. VI. p. 302.
† Tacitus, Agric. See Note (D d.)
in the short space of a hundred years, I must not here stop to inquire. Much, I apprehend, must be ascribed to our enlarged knowledge of nature, and more particularly to those scientific voyages and travels which have annihilated so many of the prodigies which exercised the wonder and subdued the reason of our ancestors. But, in whatever manner the revolution is to be explained, there can be no doubt that this growing disposition to weigh scrupulously the probability of alleged facts against the faith due to the testimonies brought to attest them, and, even in some cases, against the apparent evidence of our own senses, enters largely and essentially into the composition of that philosophical spirit or temper, which so strongly distinguishes the eighteenth century from all those which preceded it.* It it is no small consolation to reflect, that some important maxims of good sense have been thus familiarized to the most ordinary understandings, which, at so very recent a period, failed in producing their due effect on two of the most powerful minds in Europe.
On reviewing the foregoing paragraphs, I am almost tempted to retract part of what I have written, when I reflect on the benefits which the world has derived even from the errors of Leibnitz. It has been well and justly said, that every desideratum is an imperfect discovery; to which it may be added, that every new problem which is started, and still more every attempt, however abortive, towards its solution, strikes out a new path, which must sooner or later lead to the truth. If the problem be solvable, a solution will in due time be obtained: If insolvable, it will soon be abandoned as hopeless by general consent; and the legitimate field of scientific research will become more fertile, in proportion as a more accurate survey of its boundaries adapts it better to the limited resources of the cultivators.
In this point of view, what individual in modern times can be compared with Leibnitz! To how many of those researches, which still usefully employ the talents and industry of the learned, did he not point out and open
* See Note (E e.)
the way! From how many more did he not warn the wise to withhold their curiosity, by his bold and fruitless attempts to burst the barriers of the invisible world!
The best éloge of Leibnitz is furnished by the literary history of the eighteenth century;-a history which, whoever takes the pains to compare with his works, and with his epistolary correspondence, will find reason to doubt, whether, at the singular era when he appeared, he could have more accelerated the advancement of knowledge by the concentration of his studies, than he has actually done by the universality of his aims; and whether he does not afford one of the few instances to which the words of the poet may literally be applied:
"Si non errâsset, fecerat ille minus.” *
Of the Metaphysical Speculations of Newton and Clarke.-Digression with respect to the System of Spinoza.-Collins and Jonathan Edwards.-Anxiety of both to reconcile the Scheme of Necessity with Man's Moral Agency.-Departure of some later Necessitarians from their views.†
THE foregoing review of the philosophical writings of Locke and of Leibnitz naturally leads our attention, in the
See Note (F f.)
In conformity to the plan announced in the preface to this Dissertation, I confine myself to those authors whose opinions have had a marked and general influence on the subsequent history of philosophy; passing over a multitude of other names well worthy to be recorded in the annals of metaphysical science. Among these, I shall only mention the name of Boyle, to whom the world is indebted, besides some very acute remarks and many fine illustrations of his own upon metaphysical questions of the highest moment, for the philosophical arguments in defence of religion, which have added so much lustre to the names of Derham and Bentley; and, far above both, to that of Clarke.* The remarks and illustrations, which I refer to, are to be found in his Inquiry into the Vulgar Notion of Nature, and in his Essay inquiring whether, and how, a Naturalist should consider Final Causes. Both of these tracts display powers which might have placed their author on a level with Descartes and Locke, had not his taste and inclination determined him more strongly to other pursuits. I am inclined to think, that neither of them is so well known as were to be wished. I do not even recollect to have seen it anywhere noticed, that some of the most striking and beautiful instances of design in the order of the material world, which occur in the Sermons preached at Boyle's Lecture, are borrowed from the works of the founder.t
*To the English reader it is unnecessary to observe, that I allude to the Sermons preached at the Lecture founded by the Honorable Robert Boyle.
Those instances, more especially, which are drawn from the anatomical structure of animals, and the adaptation of their perceptive organs to the habits of life for which they are destined.
next place, to those of our illustrious countrymen Newton and Clarke; the former of whom has exhibited in his Principia and Optics, the most perfect exemplifications which have yet appeared, of the cautious logic recommended by Bacon and Locke; while the other, in defending against the assaults of Leibnitz the metaphysical principles on which the Newtonian philosophy proceeds, has been led, at the same time, to vindicate the authority of various other truths, of still higher importance, and more general interest.
The chief subjects of dispute between Leibnitz and Clarke, so far as the principles of the Newtonian philoso phy are concerned, have been long ago settled, to the entire satisfaction of the learned world. The monads, and the plenum, and the pre-established harmony of Leibnitz, already rank, in the public estimation, with the vortices of Descartes, and the plastic nature of Cudworth; while the theory of gravitation prevails every where over all opposition; and, as Mr. Smith remarks, "has advanced to the acquisition of the most universal empire that was ever established in philosophy." On these points, therefore, I have only to refer my readers to the collection published by Dr. Clarke, in 1717, of the controversial papers which passed between him and Leibnitz during the two preceding years; a correspondence equally curious and instructive; and which, it is to be lamented, that the death of Leibnitz in 1716 prevented from being longer continued.*
Notwithstanding, however, these great merits, he has written too little on such abstract subjects to entitle him to a place among English metaphysicians; nor has he, like Newton, started any leading thoughts which have since given a new direction to the studies of metaphysical inquirers. From the slight specimens he has left, there is reason to conclude, that his mind was still more happily turned than that of Newton, for the prosecution of that branch of science to which their contemporary Locke was then beginning to invite the attention of the public.
* From a letter of Leibnitz to M. Remond de Montmort, it appears that he considered Newton, and not Clarke, as his real antagonist in this controversy. "M. Clarke, ou plutôt M. Newton, dont M. Clarke soutient les dogmes, est en dispute avec moi sur la philosophie." (Leib. Op. Tom. V. p. 33.) From another letter to the same correspondent we learn, that Leibnitz aimed at nothing less than the complete overthrow of the Newtonian philosophy; and that it was chiefly to his grand principle of the sufficient reason that he trusted for the accomplishment of this object. "J'ai reduit l'état de notre dispute à ce grand axiome, que rien n'existe, ou n'arrive sans qu'il y ait une raison suffisante, pourquoi il en est plutôt ainsi qu'autrement. S'il continue à me le nier, où en sera sa sincerité? S'il me l'accorde, adieu le vuide, les atômes, et toute la philosophie de M. Newton.” (Ibid.)
Although Newton does not appear to have devoted much of his time to Metaphysical researches, yet the general spirit of his physical investigations has had a great, though indirect influence on the metaphysical studies of his successors. It is justly and profoundly remarked by Mr. Hume, that "while Newton seemed to draw off the veil from some of the mysteries of nature, he showed, at the same time, the imperfections of the mechanical philosophy, and thereby restored her ultimate secrets to that obscurity in which they ever did, and ever will remain." In this way, his discoveries have cooperated powerfully with the reasonings of Locke in producing a general conviction of the inadequacy of our faculties to unriddle those sublime enigmas on which Descartes, Malebranche, and Leibnitz, had so recently wasted their strength, and which, in the ancient world, were regarded as the only fit objects of philosophical curiosity. It is chiefly too since the time of Newton, that the ontology and pneumatology of the dark ages have been abandoned for inquiries. resting on the solid basis of experience and analogy; and that philosophers have felt themselves emboldened by his astonishing discoveries concerning the more distant parts of the material universe, to argue from the known to the unknown parts of the moral world. So completely has the prediction been verified which he himself hazarded, in the form of a query, at the end of his Optics, that "if natural philosophy should continue to be improved in its various branches, the bounds of moral philosophy would be enlarged also."
How far the peculiar cast of Newton's genius qualified him for prosecuting successfully the study of Mind, he has not afforded us sufficient data for judging; but such was the admiration with which his transcendent powers as a Mathematician and Natural Philosopher were universally regarded, that the slightest of his hints on the other subjects have been eagerly seized upon as indisputable axioms, though sometimes with little other evidence in their favor but the supposed sanction of his authority.*
See also a letter from Leibnitz to M. des Maizeaux in the same volume of his works, p. 39.
* Witness Hartley's Physiological Theory of the Mind, founded on a query in