Sir Isaac's philosophy, particularly his opinions about gravity and vacuum, the intervention of God for the preservation of his creatures; and he accuses him of reviving the occult qualities of the schools. But the most remarkable passage in this letter is the following: "I am a great friend of experimental philosophy, but Newton deviates much from it when he pretends that all matter is heavy, or that each particle of matter attracts every other particle."

The above letter to the Abbé Conti was generally shown in London, and came to be much talked of at court, in consequence of Leibnitz having been privy counsellor to the Elector of Hanover when that prince ascended the throne of England. Many persons of distinction, and particularly the Abbé Conti, urged Newton to reply to Leibnitz's letter, but he resisted all their solicitations. One day, however, King George I. inquired when Sir Isaac Newton's answer to Leibnitz would appear; and when Sir Isaac heard this, he addressed a long reply to the Abbé Conti, dated February 26th, O. S. 171516. This letter, written with dignified severity, is a triumphant refutation of the allegations of his adversary; and the following passage deserves to be quoted, as connected with that branch of the dispute which relates to Leibnitz's having seen part of Newton's letters to Mr. Collins. "He complains of the committee of the Royal Society, as if they had acted partially in omitting what made against me; but he fails in proving the accusation. For he instances in a paragraph concerning my ignorance, pretending that they omitted it, and yet you will find it in the Commercium Epistolicum, p. 547, lines 2, 3, and I am not ashamed of it. He saith that he saw this paragraph in the hands of Mr. Collins when he was in London the second time, that is in October, 1676. It is in my letter of the 24th of October, 1676, and therefore he then saw that letter. And

in that and some other letters writ before that time, I described my method of fluxions; and in the same letter I described also two general methods of series, one of which is now claimed from me by Mr. Leibnitz." The letter concludes with the following paragraph: "But as he has lately attacked me with an accusation which amounts to plagiary; if he goes on to accuse me, it lies upon him by the laws of all nations to prove his accusations, on pain of being accounted guilty of calumny. He hath hitherto written letters to his correspondents full of affirmations, complaints, and reflections, without proving any thing. But he is the aggressor, and it lies upon him to prove the charge."

In transmitting this letter to Leibnitz, the Abbé Conti informed him that he himself had read with great attention, and without the least prejudice, the Commercium Epistolicum, and the little piece* that contains the extract; that he had also seen at the Royal Society the original papers of the Commercium Epistolicum, and some other original pieces relating to it. "From all this," says he, "I infer, that, if all the digressions are cut off, the only point is, whether Sir Isaac Newton had the method of fluxions or infinitesimals before you, or whether you had it before him. You published it first, it is true, but you have owned also that Sir Isaac Newton had given many hints of it in his letters to Mr. Oldenburg and others. This is proved very largely in the Commercium, and in the extract of it. What answer do you give? This is still wanting to the public, in order to form an exact judgment of the affair." The Abbé adds, that Mr. Leibnitz's own friends waited for his answer with great impatience, and that they thought he could not dispense with answering, if not Dr. Keill, at least Sir Isaac New

*This is the Recensio Commercii Fpistolici, or review of it, which was first published in the Phil. Trans, 1715.

ton himself, who had given him a defiance in express

terms.

Leibnitz was not long in complying with this request. He addressed a letter to the Abbé Conti, dated April 9th, 1716, but he sent it through M. Ramond at Paris, to communicate it to others. When it was received by the Abbé Conti, Newton wrote observations upon it, which were communicated only to some of his friends, and which, while they placed his defence on the most impregnable basis, at the same time threw much light on the early history of his mathematical discoveries.

The death of Leibnitz on the 14th November, 1716, put an end to this controversy, and Newton some time afterward published the correspondence with the Abbé Conti, which had hitherto been only privately circulated among the friends of the disputants.*

In 1722, a new edition of the Commercium Epistolicum was published, and there was prefixed to it a general review of its contents, which has been falsely ascribed to Newton.† When the third edi

* M. Biot remarks, that the animosity of Newton was not calmed by the death of Leibnitz, for he had no sooner heard of it than he caused to be printed two manuscript letters of Leibnitz, written in the preceding year, accompanying them with a very bitter refutation (en les accompagnant d'un refutation tres-amere). Who that reads this sentence does not believe that the bitter refutation was written after Leibnitz's death? The animosity could not be shown by the simple publication of the letters. It could reside only in the bitterness of the refutation. The implied charge is untrue; the bitter refutation was written before Leibnitz's death, and consequently he showed no animosity over the grave of his rival; and in our opinion none even before his death.

↑ M. Biot states that Sir Isaac Newton caused this edition of the Commercium Epistolicum to be printed; that Sir Isaac placed at the head of it a partial abstract of the collection; and that this abstract appeared to have been written by himself. These groundless charges may be placed, without any refutation, beside the assertion of Montucla, that Newton wrote the notes (les notes) on the Commercium Epistolicum; and the equally incorrect statement of La Croix, that Newton added to it notes (des notes), with his own hand. We should not have noticed the charges of M. Biot, had he not adduced them as proofs of Newton's animosity to Leibnitz after his death. See Mr. Herschel's History of Mathematics in the Edinburgh Encyclopædią, vol. xiii. p. 368, note.

tion of the Principia was published in 1725, the celebrated scholium which we have already quoted, and in which Leibnitz's differential calculus was mentioned, was struck out either by Newton or by the editor. This step was perhaps rash and illadvised; but as the scholium had been adduced by Leibnitz and others as a proof that Newton acknowledged him to be an independent inventor of the calculus, an interpretation which it does not bear, and which Newton expressly states he never intended it to bear, he was justified in withdrawing a passage which had been so erroneously interpreted, and so greatly misapplied.

In viewing this controversy, at the distance of more than a century, when the passions of the individual combatants have been allayed, and national jealousies extinguished, it is not difficult to form a correct estimate of the conduct and claims of the two rival analysts. By the unanimous verdict of all nations, it has been decided that Newton invented fluxions at least ten years before Leibnitz. Some of the letters of Newton which bore reference to this great discovery were perused by the German mathematician; but there is no evidence whatever that he borrowed his differential calculus from these letters. Newton was therefore the first inventor, and Leibnitz the second. It was impossible that the former could have been a plagiarist; but it was possible for the latter. Had the letters of Newton contained even stronger indications than they do of the new calculus, no evidence short of proof could have justified any allegation against Leibnitz's honour. The talents which he displayed in the im provement of the calculus showed that he was capable of inventing it; and his character stood sufficiently high to repel every suspicion of his integrity. But if it would have been criminal to charge Leibnitz with plagiarism, what must we think of those who dared to accuse Newton of bor

rowing his fluxions from Leibnitz? This odious accusation was made by Leibnitz himself, and by Bernouilli; and we have seen that the former repeated it again and again, as if his own good name rested on the destruction of that of his rival. It was this charge against Newton that gave rise to the attack of Keill, and the publication of the Commercium Epistolicum; and, notwithstanding this high provocation, the committee of the Royal Society contented themselves with asserting Newton's priority, without retorting the charge of plagiarism upon his rival.

Although an attempt has been recently made to place the conduct of Leibnitz on the same level with that of Newton, yet the circumstances of the case will by no means justify such a comparison. The conduct of Newton was at all times dignified and just. He knew his rights, and he boldly claimed them. Conscious of his integrity, he spurned with indignation the charge of plagiarism with which an ungenerous rival had so insidiously loaded him; and if there was one step in his frank and unhesitating procedure which posterity can blame it is his omission, in the third edition of the Principia, of the references to the differential calculus of Leibnitz. This omission, however, was perfectly just. The scholium which he had left out was a mere historical statement of the fact, that the German mathematician had sent him a method which was the same as his own; and when he found that this simple assertion had been held by Leibnitz and others as a recognition of his independent claim to the invention, he was bound either to omit it altogether, or to enter into explanations which might have involved him in a new controversy.

The conduct of Leibnitz was not marked with the same noble lineaments. That he was the aggressor is universally allowed. That he first dared to breathe the charge of plagiarism against Newton, and that he often referred to it, has been sufficiently