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cheerful than gay, or, at least, never rose to any turbulence or tumult of merriment; and while he would listen with the kindest indulgence to the more extravagant sallies of his younger friends, and prompt them by the heartiest approbation, his own satisfaction might generally be traced in a quiet and temperate smile, gradually mantling over his benevolent and intelligent features, and lighting up the countenance of the sage with the expression of the mildest and most genuine philanthropy. It was wonderful, indeed, considering the measure of his own intellect, and the rigid and undeviating propriety of his own conduct, how tolerant he was of the defects and errors of other men.

Independent, in short, of his high attainments, Mr. Playfair was one of the most amiable and estimable of men. Delightful in his manners, inflexible in his principles, and generous in his affections, he had all that could charm in society.or attach in private; and whilst he enjoyed the free and unstudied conversation of intelligent associates, they had at all times the assurance that he was a being upon whose perfect honor and generosity they might rely, with the most implicit confidence, in life and in death.

LESSON CVI.

Parallel between Leibnitz and Newton.-PLAYFAIR.

A

FOR the variety of his genius, and the extent of his research, Leibnitz is, perhaps, altogether unrivalled. lawyer, a historian, an antiquary, a poet and a philologist, a mathematician, a metaphysician, a theologian, and, I will add, a geologist,-he has in all these characters produced works of great merit, and, in some of them, of the highest excellence. It is rare that original genius has so little of a peculiar direction, or is disposed to scat

ter its efforts over so wide a field. Though a man of great inventive powers, he occupied much of his time in works of mere labor and erudition, where there was nothing to invent, and not much of importance to discover.

Newton did not aim at so wide a range. Fortunately for himself and for the world, his genius was more determined to a particular point, and its effects were more concentrated. Their direction was to the accurate sciences, and they soon proved equally inventive in the pure and in the mixed mathematics. Newton knew how to transfer the truths of abstract science to the study of things actually existing, and, by returning in the opposite direction, to enrich the former by ideas derived from the latter. In experimental and inductive investigation, he was as great as in the pure mathematics, and his discoveries were as distinguished in the one as in the other. In this double claim to renown, Newton stands yet unrivalled; and though, in the pure mathematics, equals may, perhaps, be found, no one, I believe, will come forward as his rival both in that science and in the philosophy of nature.

His caution in adopting general principles; his dislike to what was vague or obscure; his rejection of all theories from which precise conclusions cannot be deduced; and his readiness to relinquish those that depart in any degree from the truth, are, throughout, the characters of his philosophy, and distinguish it very essentially from the philosophy of Leibnitz. The characters now enumerated are most of them negative, but without the principles on which they are founded, invention can hardly be kept in the right course. The German philosopher was not furnished with them in the same degree as the English, and hence his great talents have run very frequently to waste.

It may be doubted, also, whether Leibnitz's great metaphysical acuteness did not sometimes mislead him in the study of nature, by inclining him to those reasonings which proceed, or affect to proceed, continually from the cause to the effect. The attributes of the Deity were the

axioms of his philosophy; and he did not reflect that this foundation, excellent in itself, lies much too deep for a structure that is to be raised by so feeble an architect as man; or that an argument, which sets out with the most profound respect to the Supreme Being, usually terminates in the most unwarrantable presumption. His reasonings from first causes are always ingenious; but nothing can prevent the substitution of such causes for those that are physical and efficient, from being one of the worst and most fatal errors in philosophy.

As an interpreter of nature, therefore, Leibnitz stands in no comparison with Newton. As to who benefited human knowledge most, no question can arise; and if genius is to be weighed in this balance, it is evident which scale must preponderate. Except in the pure mathematics, Leibnitz, with all his talents, made no material or permanent addition to the sciences. Newton, to equal inventions in mathematics, added the greatest discoveries in the philosophy of nature; and, in passing through his hands, mechanics, optics and astronomy were not merely improved, but renovated. No one ever left knowledge in a state so different from that in which he found it. Men were instructed not only in new truths, but in new methods of discovering truths. They were made acquainted with the great principle which connects together the most distant regions of space, as well as the most remote periods of duration; and which was to lead to future discoveries, far beyond what the wisest or most sanguine could anticipate.

LESSON CVII.

Genius of Laplace.-PROFESSOR PLAYFAIR.

THE work of Laplace affords an example, which is yet solitary in the history of human knowledge, of a theory

entirely complete; one that has not only accounted for all the phenomena that were known, but that has discovered many before unknown, which observation has since recognized.

In this theory, not only the elliptic motion of the planets, relatively to the sun, but the irregularities produced by their mutual action, whether of the primary on the primary, or of the primary on the secondary, or of the secondary on one another, are all deduced from the principle of gravitation, that mysterious power, which unites the most distant regions of space, and the most remote periods of duration. To this we must add the great truths brought into view, and fully demonstrated, by tracing the action of the same power through all its mazes ;—that all the inequalities in our system are periodical; that, by a fixed appointment in nature, they are each destined to revolve in the same order, and between the same limits; that the mean distances of the planets from the sun, and the time of their revolutions round that body, are susceptible of no change whatsoever; that our system is thus secured against natural decay, order and regularity preserved in the midst of so many disturbing causes, and anarchy and misrule eternally proscribed.

The work where this sublime picture is delineated, does honor, not to the author only, but to the human race, and marks, undoubtedly, the highest point to which man has yet ascended in the scale of intellectual attainment. The glory, therefore, of having produced this work (the Mécanique Céleste) belongs not to the author alone, but must be shared, in various proportions, among the philosophers and mathematicians of all ages. Their efforts, from the age of Euclid and Archimedes to the time of Newton and Laplace, have all been required to the accomplishment of this great object; they have been all necessary to form one man for the author, and a few for the readers, of the work before us. Every mathematician who has extended the bounds of his science; every astronomer who has added to the number of facts, and who

has increased the accuracy of observation; every artist who has improved the construction of the instruments of astronomy-all have coöperated in preparing a state of knowledge in which such a book could exist, and in which its merit could be appreciated. They have collected the materials, sharpened the tools, or constructed the engines employed in the great edifice, founded by Newton, and completed by Laplace.

In this estimate we detract nothing from the merit of the author himself; his originality, his invention and comprehensive views are above all praise; nor can any man boast of a higher honor than that the genius of the human race is the only rival of his fame.*

LESSON CVIII.

The Ocean an Image of Eternity.-BYRON.

ROLL on, thou deep and dark blue ocean-roll!
Ten thousand fleets sweep over thee in vain;
Man marks the earth with ruin-his control

Stops with the shore ;-upon the watery plain
The wrecks are all thy deed, nor doth remain
A shadow of man's ravage, save his own,

When, for a moment, like a drop of rain,
He sinks into thy depths with bubbling groan,
Without a grave, unknelled, uncoffined and unknown.

His steps are not upon thy paths,―thy fields
Are not a spoil for him,-thou dost arise

* Professor Playfair said that the number of those in Great Britain who could read the work of Laplace, with any tolerable facility, did not exceed two or three in London and the military schools in its vicinity, the same number at each of the two English universities, and perhaps four in Scotland-about twelve in all. This work is now in the process of translation by Dr. Bowditch of Boston. Two volumes have been published.

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