James II. attacks the Privileges of the University of Cambridge—Newton chosen one of the Delegates to resist this Encroachment—He is elected a Member of the Convention Parliament—Burning of his Manuscripts—His supposed Derangement of Mind—View taken of this by foreign Philosophers—His Correspondence with Mr. Pepys and Mr. Locke at the time of his Illness—Mr. Millington’s Letter to Mr. Pepys on the subject of Newton’s Illness—Refutation of the Statement that he laboured under Mental Derangement.

From the year 1669, when Newton was installed in the Lucasian chair, till 1695, when he ceased to reside in Cambridge, he seems to have been seldom absent from his college more than three or four weeks in the year. In 1675, he received a dispensation from Charles II. to continue in his fellowship of Trinity College without taking orders, and we have already seen in the preceding chapter how his time was occupied till the publication of the Principia in 1687.

An event now occurred which drew Newton from the seclusion of his studies, and placed him upon the theatre of public life. Desirous of re-establishing the Catholic faith in its former supremacy, King James II. had begun to assail the rights and privileges of his Protestant subjects. Among other illegal acts, he sent his letter of mandamus to the University of Cambridge to order Father Francis, an ignorant monk of the Benedictine order, to be received as master of arts, and to enjoy all the privileges of this degree, without taking the oaths of allegiance and supremacy. The university speedily perceived the consequences which might arise from such a measure. Independent of the infringement of their rights which such an order involved, it was obvious that the highest interests of the university were endangered, and that Roman Catholics might soon become a majority in the convocation. They therefore unanimously refused to listen to the royal order, and they did this with a firmness of purpose which irritated the despotic court. The king reiterated his commands, and accompanied them with the severest threatenings in case of disobedience. The Catholics were not idle in supporting the views of the sovereign. The honorary degree of M.A. which conveys no civil rights to its possessor, having been formerly given to the secretary of the ambassador from Morocco, it was triumphantly urged that the University of Cambridge had a greater regard for a Mahometan than for a Roman Catholic, and was more obsequious to the ambassador from Morocco than to their own lawful sovereign. Though this reasoning might impose upon the ignorant, it produced little effect upon the members of the university. A few weak-minded individuals, however, were disposed to yield a reluctant consent to the royal wishes. They proposed to confer the degree, and at the same time to resolve that it should not in future be regarded as a precedent. To this it was replied, that the very act of submission in one case would be a stronger argument for continuing the practice than any such resolution would be against its repetition. The university accordingly remained firm in their original decision. The vice-chancellor was summoned before the ecclesiastical commission to answer for this act of contempt. Newton was among the number of those who resisted the wishes of the court, and he was consequently chosen one of the nine delegates who were appointed to defend the independence of the university. These delegates appeared before the High Court. They maintained that not a single precedent could be found to justify so extraordinary a measure; and they showed that Charles II. had, under similar circumstances, been pleased to withdraw his mandamus. This representation had its full weight, and the king was induced to abandon his design.73

The part which Newton had taken in this affair, and the high character which he now held in the scientific world, induced his friends to propose him as member of parliament for the university. He was accordingly elected in 1688, though by a very narrow majority,74 and he sat in the Convention Parliament till its dissolution. In the year 1688 and 1689, Newton was absent from Cambridge during the greater part of the year, owing, we presume, to his attendance in parliament; but it appears from the books of the University that from 1690 to 1695 he was seldom absent, and must therefore have renounced his parliamentary duties.

During his stay in London he had no doubt experienced the unsuitableness of his income to the new circumstances in which he was placed, and it is probable that this was the cause of the limitation of his residence to Cambridge. His income was certainly very confined, and but little suited to the generosity of his disposition. Demands were doubtless made upon it by some of his less wealthy relatives; and there is reason to think that he himself, as well as his influential friends, had been looking forward to some act of liberality on the part of the government.

An event however occurred which will ever form an epoch in his history; and it is a singular circumstance, that this incident has been for more than a century unknown to his own countrymen, and has been accidentally brought to light by the examination of the manuscripts of Huygens. This event has been magnified into a temporary aberration of mind, which is said to have arisen from a cause scarcely adequate to its production.

While he was attending divine service in a winter morning, he had left in his study a favourite little dog called Diamond. Upon returning from chapel he found that it had overturned a lighted taper on his desk, which set fire to several papers on which he had recorded the results of some optical experiments. These papers are said to have contained the labours of many years, and it has been stated that when Mr. Newton perceived the magnitude of his loss, he exclaimed, “Oh, Diamond, Diamond, little do you know the mischief you have done me!” It is a curious circumstance that Newton never refers to the experiments which he is said to have lost on this occasion, and his nephew, Mr. Conduit, makes no allusion to the event itself. The distress, however which it occasioned is said to have been so deep as to affect even the powers of his understanding.

This extraordinary effect was first communicated to the world in the Life of Newton by M. Biot, who received the following account of it from the celebrated M. Van Swinden.

“There is among the manuscripts of the celebrated Huygens a small journal in folio, in which he used to note down different occurrences. It is side ?, No. 8, p. 112, in the catalogue of the library of Leyden. The following extract is written by Huygens himself, with whose handwriting I am well acquainted, having had occasion to peruse several of his manuscripts and autograph letters. ‘On the 29th May, 1694, M. Colin,75 a Scotsman, informed me that eighteen months ago the illustrious geometer, Isaac Newton, had become insane, either in consequence of his too intense application to his studies, or from excessive grief at having lost, by fire, his chymical laboratory and several manuscripts. When he came to the Archbishop of Cambridge, he made some observations which indicated an alienation of mind. He was immediately taken care of by his friends, who confined him to his house and applied remedies, by means of which he had now so far recovered his health that he began to understand the Principia.’” Huygens mentioned this circumstance to Leibnitz, in a letter dated 8th June, 1694, to which Leibnitz replies in a letter dated the 23d, “I am very glad that I received information of the cure of Mr. Newton, at the same time that I first heard of his illness, which doubtless must have been very alarming. ‘It is to men like you and him, sir, that I wish a long life.’”

The first publication of the preceding statement produced a strong sensation among the friends and admirers of Newton. They could not easily believe in the prostration of that intellectual strength which had unbarred the strongholds of the universe. The unbroken equanimity of Newton’s mind, the purity of his moral character, his temperate and abstemious life, his ardent and unaffected piety, and the weakness of his imaginative powers, all indicated a mind which was not likely to be overset by any affliction to which it could be exposed. The loss of a few experimental records could never have disturbed the equilibrium of a mind like his. If they were the records of discoveries, the discoveries themselves indestructible would have been afterward given to the world. If they were merely the details of experimental results, a little time could have easily reproduced them. Had these records contained the first fruits of early genius—of obscure talent, on which fame had not yet shed its rays, we might have supposed that the first blight of such early ambition would have unsettled the stability of an untried mind. But Newton was satiated with fame. His mightiest discoveries were completed and diffused over all Europe, and he must have felt himself placed on the loftiest pinnacle of earthly ambition. The incredulity which such views could not fail to encourage was increased by the novelty of the information. No English biographer had ever alluded to such an event. History and tradition were equally silent, and it was not easy to believe that the Lucasian Professor of Mathematics at Cambridge, a member of the English parliament, and the first philosopher in Europe could have lost his reason without the dreadful fact being known to his own countrymen.

But if the friends of Newton were surprised by the nature of the intelligence, they were distressed at the view which was taken of it by foreign philosophers. While one maintained that the intellectual exertions of Newton had terminated with the publication of the Principia, and that the derangement of his mind was the cause of his abandoning the sciences, others indirectly questioned the sincerity of his religious views, and ascribed to the aberration of his mind those theological pursuits which gilded his declining age. “But the fact,” says M. Biot, “of the derangement of his intellect, whatever may have been the cause of it, will explain why, after the publication of the Principia in 1687, Newton, though only forty-five years old, never more published a new work on any branch of science, but contented himself with giving to the world those which he had composed long before that epoch, confining himself to the completion of those parts which might require development. We may also remark, that even these developments appear always to be derived from experiments and observations formerly made, such as the additions to the second edition of the Principia, published in 1713, the experiments on thick plates, those on diffraction, and the chymical queries placed at the end of the Optics in 1704; for in giving an account of these experiments Newton distinctly says that they were taken from ancient manuscripts which he had formerly composed; and he adds, that though he felt the necessity of extending them, or rendering them more perfect, he was not able to resolve to do this, these matters being no longer in his way. Thus it appears that though he had recovered his health sufficiently to understand all his researches, and even in some cases to make additions to them, and useful alterations, as appears from the second edition of the Principia, for which he kept up a very active mathematical correspondence with Mr. Cotes, yet he did not wish to undertake new labours in those departments of science where he had done so much, and where he so distinctly saw what remained to be done.” Under the influence of the same opinion, M. Biot finds “it extremely probable that his dissertation on the scale of heat was written before the fire in his laboratory;” he describes Newton’s conduct about the longitude bill as “almost puerile on so solemn an occasion, and one which might lead to the strangest conclusions, particularly if we refer it to the fatal accident which Newton had suffered in 1695.”

The celebrated Marquis de la Place viewed the illness of Newton in a light still more painful to his friends. He maintained that he never recovered the vigour of his intellect, and he was persuaded that Newton’s theological inquiries did not commence till after that afflicting epoch of his life. He even commissioned Professor Gautier of Geneva to make inquiries on this subject during his visit to England, as if it concerned the interests of truth and justice to show that Newton became a Christian and a theological writer only after the decay of his strength and the eclipse of his reason.

Such having been the consequences of the disclosure of Newton’s illness by the manuscript of Huygens, I felt it to be a sacred duty to the memory of that great man, to the feelings of his countrymen, and to the interests of Christianity itself, to inquire into the nature and history of that indisposition which seems to have been so much misrepresented and misapplied. From the ignorance of so extraordinary an event which has prevailed for such a long period in England, it might have been urged with some plausibility that Huygens had mistaken the real import of the information that was conveyed to him; or that the Scotchman from whom he received it had propagated an idle and a groundless rumour. But we are, fortunately, not confined to this very reasonable mode of defence. There exists at Cambridge a manuscript journal written by Mr. Abraham de la Pryme, who was a student in the university while Newton was a fellow of Trinity. This manuscript is entitled “Ephemeris VitÆ, or Diary of my own Life, containing an account likewise of the most observable and remarkable things that I have taken notice of from my youth up hitherto.” Mr. de la Pryme was born in 1671, and begins the diary in 1685. This manuscript is in the possession of his collateral descendant, George Pryme, Esq., Professor of Political Economy at Cambridge, to whom I have been indebted for the following extract.

“1692, February 3d.—What I heard to-day I must relate. There is one Mr. Newton (whom I have very oft seen), Fellow of Trinity College, that is mighty famous for his learning, being a most excellent mathematician, philosopher, divine, &c. He has been Fellow of the Royal Society these many years; and among other very learned books and tracts, he’s written one upon the mathematical principles of philosophy, which has got him a mighty name, he having received, especially from Scotland, abundance of congratulatory letters for the same; but of all the books that he ever wrote, there was one of colours and light, established upon thousands of experiments which he had been twenty years of making, and which had cost him many hundred of pounds. This book, which he valued so much, and which was so much talked of, had the ill luck to perish and be utterly lost just when the learned author was almost at putting a conclusion at the same, after this manner: In a winter’s morning, leaving it among his other papers on his study table while he went to chapel, the candle, which he had unfortunately left burning there too, catched hold by some means of other papers, and they fired the aforesaid book, and utterly consumed it and several other valuable writings; and, which is most wonderful, did no further mischief. But when Mr. Newton came from chapel, and had seen what was done, every one thought he would have run mad, he was so troubled thereat that he was not himself for a month after. A long account of this his system of light and colours you may find in the Transactions of the Royal Society, which he had sent up to them long before this sad mischance happened unto him.”

From this extract we are enabled to fix the approximate date of the accident by which Newton lost his papers. It must have been previous to the 3d January, 1692, a month before the date of the extract; but if we fix it by the dates in Huygens’s manuscript, we should place it about the 29th November, 1692, eighteen months previous to the conversation between Collins and Huygens. The manner in which Mr. Pryme refers to Newton’s state of mind is that which is used every day when we speak of the loss of tranquillity which arises from the ordinary afflictions of life; and the meaning of the passage amounts to nothing more than that Newton was very much troubled by the destruction of his papers, and did not recover his serenity, and return to his usual occupations, for a month. The very phrase that “every person thought he would have run mad” is in itself a proof that no such effect was produced; and, whatever degree of indisposition may be implied in the phrase “he was not himself for a month after,” we are entitled to infer that one month was the period of its duration, and that previous to the 3d February, 1692, the date of Mr. Pryme’s memorandum, “Newton was himself again.”

These facts and dates cannot be reconciled with those in Huygens’s manuscript. It appears from that document, that, so late as May, 1694, Newton had only so far recovered his health as to begin to again understand the Principia. His supposed malady, therefore, was in force from the 3d of January, 1692, till the month of May, 1694,—a period of more than two years. Now, it is a most important circumstance, which M. Biot ought to have known, that in the very middle of this period, Newton wrote his four celebrated letters to Dr. Bentley on the Existence of a Deity,—letters which evince a power of thought and a serenity of mind absolutely incompatible even with the slightest obscuration of his faculties. No man can peruse these letters without the conviction that their author then possessed the full vigour of his reason, and was capable of understanding the most profound parts of his writings. The first of these letters was written on the 10th December, 1692, the second on the 17th January, 1693, the third on the 25th February, and the 4th on the 11th76 February, 1693. His mind was, therefore, strong and vigorous on these four occasions; and as the letters were written at the express request of Dr. Bentley, who had been appointed to deliver the lecture founded by Mr. Boyle for vindicating the fundamental principles of natural and revealed religion, we must consider such a request as showing his opinion of the strength and freshness of his friend’s mental powers.

In 1692, Newton, at the request of Dr. Wallis, transmitted to him the first proposition of his book on quadratures, with examples of it in first, second, and third fluxions.77 These examples were written in consequence of an application from his friend; and the author of the review of the Commercium Epistolicum, in which this fact is quoted, draws the conclusion, that he had not at that time forgotten his method of second fluxions. It appears, also, from the second book of the Optics,78 that in the month of June, 1692, he had been occupied with the subject of haloes, and had made accurate observations both on the colours and the diameters of the rings in a halo which he had then seen around the sun. But though these facts stand in direct contradiction to the statement recorded by Huygens, the reader will be naturally anxious to know the real nature and extent of the indisposition to which it refers. The following letters,79 written by Newton himself, Mr. Pepys, Secretary to the Admiralty, and Mr. Millington of Magdalene College, Cambridge, will throw much light upon the subject.

Newton, as will be presently seen, had fallen into a bad state of health some time in 1692, in consequence of which both his sleep and his appetite were greatly affected. About the middle of September, 1693, he had been kept awake for five nights by this nervous disorder, and in this condition he wrote the following letter to Mr. Pepys:

Sept. 13, 1693.

“Sir,

“Some time after Mr. Millington had delivered your message, he pressed me to see you the next time I went to London. I was averse; but upon his pressing consented, before I considered what I did, for I am extremely troubled at the embroilment I am in, and have neither ate nor slept well this twelvemonth, nor have my former consistency of mind. I never designed to get any thing by your interest, nor by King James’s favour, but am now sensible that I must withdraw from your acquaintance, and see neither you nor the rest of my friends any more, if I may but leave them quietly. I beg your pardon for saying I would see you again, and rest your most humble and most obedient servant,

“I^s. Newton.”

From this letter we learn, on his own authority, that his complaint had lasted for a twelvemonth, and that during that twelvemonth he neither ate nor slept well, nor enjoyed his former consistency of mind. It is not easy to understand exactly what is meant by not enjoying his former consistency of mind; but whatever be its import, it is obvious that he must have been in a state of mind so sound as to enable him to compose the four letters to Bentley, all of which were written during the twelvemonth here referred to.

On the receipt of this letter, his friend Mr. Pepys seems to have written to Mr. Millington of Magdalene College to inquire after Mr. Newton’s health; but the inquiry having been made in a vague manner, an answer equally vague was returned. Mr. Pepys, however, who seems to have been deeply anxious about Newton’s health, addressed the following more explicit letter to his friend Mr. Millington:—

Septemb. 26, 1693.

“Sir,

“After acknowledging your many old favours, give me leave to do it a little more particularly upon occasion of the new one conveyed to me by my nephew Jackson. Though, at the same time, I must acknowledge myself not at the ease I would be glad to be at in reference to the excellent Mr. Newton; concerning whom (methinks) your answer labours under the same kind of restraint which (to tell you the truth) my asking did. For I was loth at first dash to tell you that I had lately received a letter from him so surprising to me for the inconsistency of every part of it, as to be put into great disorder by it, from the concernment I have for him, lest it should arise from that which of all mankind I should least dread from him and most lament for,—I mean a discomposure in head, or mind, or both. Let me therefore beg you, sir, having now told you the true ground of the trouble I lately gave you, to let me know the very truth of the matter, as far at least as comes within your knowledge. For I own too great an esteem for Mr. Newton, as for a public good, to be able to let any doubt in me of this kind concerning him lie a moment uncleared, where I can have any hopes of helping it. I am, with great truth and respect, dear sir, your most humble, and most affectionate servant,

“S. Pepys.”

To this letter Mr. Millington made the following reply:—

Coll. Magd. Camb.
Sept. the 30, 1693.

“Honor’d Sir,

“Coming home from a journey on the 28th instant at night, I met with your letter which you were pleased to honour me with of the 26th. I am much troubled I was not at home in time for the post, that I might as soon as possible put you out of your generous payne that you are in for the worthy Mr. Newton. I was, I must confess, very much surprised at the inquiry you were pleased to make by your nephew about the message that Mr. Newton made the ground of his letter to you, for I was very sure I never either received from you or delivered to him any such, and therefore I went immediately to wayt upon him, with a design to discourse him about the matter, but, he was out of town, and since I have not seen him, till upon the 28th I met him at Huntingdon, where, upon his own accord, and before I had time to ask him any question, he told me that he had writt to you a very odd letter, at which he was much concerned; added, that it was in a distemper that much seized his head, and that kept him awake for above five nights together, which upon occasion he desired I would represent to you, and beg your pardon, he being very much ashamed, he should be so rude to a person for whom he hath so great an honour. He is now very well, and, though I fear he is under some small degree of melancholy, yet I think there is no reason to suspect it hath at all touched his understanding, and I hope never will; and so I am sure all ought to wish that love learning or the honour of our nation, which it is a sign how much it is looked after, when such a person as Mr. Newton lyes so neglected by those in power. And thus, honoured sir, I have made you acquainted with all I know of the cause of such inconsistencys in the letter of so excellent a person; and I hope it will remove the doubts and fears you are, with so much compassion and publickness of spirit, pleased to entertain about Mr. Newton; but if I should have been wanting in any thing tending to the more full satisfaction, I shall, upon the least notice, endeavour to amend it with all gratitude and truth. Honored sir, your most faithfull and most obedient servant,

“Joh. Millington.”

Mr. Pepys was perfectly satisfied with this answer, as appears from the following letter:—

October 3d, 1693.

“Sir,

“You have delivered me from a fear that indeed gave me much trouble, and from my very heart I thank you for it; an evil to Mr. Newton being what every good man must feel for his own sake as well as his. God grant it may stopp here. And for the kind reflection hee has since made upon his letter to mee, I dare not take upon mee to judge what answer I should make him to it, or whether any or no; and therefore pray that you will bee pleased either to bestow on mee what directions you see fitt for my own guidance towards him in it, or to say to him in my name, but your own pleasure, whatever you think may be most welcome to him upon it, and most expressive of my regard and affectionate esteem of him, and concernment for him. * * *

Dear sir, your most humble and most faithful servant,

“S. Pepys.”

It does not appear from the memoirs of Mr. Pepys whether he ever returned any answer to the letter of Mr. Newton which occasioned this correspondence; but we find that in less than two months after the date of the preceding letter, an opportunity occurred of introducing to him a Mr. Smith, who wished to have his opinion on some problem in the doctrine of chances. This letter from Pepys is dated November 22d, 1693. Sir Isaac replied to it on the 26th November, and wrote to Pepys again on the 16th December, 1693; and in both these letters he enters fully into the discussion of the mathematical question which had been submitted to his judgment.80

It is obvious, from Newton’s letter to Mr. Pepys, that the subject of his receiving some favour from the government had been a matter of anxiety with himself, and of discussion among his friends.81 Mr. Millington was no doubt referring to this anxiety, when he represents Newton as an honour to the nation, and expresses his surprise “that such a person should lye so neglected by those in power.” And we find the same subject distinctly referred to in two letters written to Mr. Locke during the preceding year. In one of these, dated January 26th, 1691–2, he says, “Being fully convinced that Mr. Montague, upon an old grudge which I thought had been worn out, is false to me, I have done with him, and intend to sit still, unless my Lord Monmouth be still my friend.” Mr. Locke seems to have assured him of the continued friendship of this nobleman, and Mr. Newton, still referring to the same topic, in a letter dated February 16th, 1691–2, remarks, “I am very glad Lord Monmouth is still my friend, but intend not to give his lordship and you any farther trouble. My inclinations are to sit still.” In a later letter to Mr. Locke, dated September, 1693, and given below, he asks his pardon for saying or thinking that there was a design to sell him an office. In these letters Mr. Newton no doubt referred to some appointment in London which he was solicitous to obtain, and which Mr. Montague and his other friends may have failed in procuring. This opinion is confirmed by the letter of Mr. Montague announcing to him his appointment to the wardenship of the mint, in which he says that he is very glad he can at last give him good proof of his friendship.

In the same month in which Newton wrote to Mr. Pepys, we find him in correspondence with Mr. Locke. Displeased with his opinions respecting innate ideas, he had rashly stated that they struck at the root of all morality; and that he regarded the author of such doctrines as a Hobbist. Upon reconsidering these opinions, he addressed the following remarkable letter to Locke, written three days after his letter to Mr. Pepys, and consequently during the illness under which he then laboured.

“Sir,

“Being of opinion that you endeavoured to embroil me with women, and by other means, I was so much affected with it, as that when one told me you were sickly and would not live, I answered, ’twere better if you were dead. I desire you to forgive me this uncharitableness; for I am now satisfied that what you have done is just, and I beg your pardon for my having hard thoughts of you for it, and for representing that you struck at the root of morality, in a principle you laid in your book of ideas, and designed to pursue in another book, and that I took you for a Hobbist.82 I beg your pardon also for saying or thinking that there was a design to sell me an office, or to embroil me.—I am your most humble and unfortunate servant,

“I^s. Newton.

“At the Bull, in Shoreditch, London,
Sept. 16th, 1693.”

To this letter Locke returned the following answer, so nobly distinguished by philosophical magnanimity and Christian charity:—

Oates, Oct. 5th, 1693.

“Sir,

“I have been, ever since I first knew you, so entirely and sincerely your friend, and thought you so much mine, that I could not have believed what you tell me of yourself had I had it from anybody else. And, though I cannot but be mightily troubled that you should have had so many wrong and unjust thoughts of me, yet next to the return of good offices, such as from a sincere good-will I have ever done you, I receive your acknowledgment of the contrary as the kindest thing you have done me, since it gives me hopes I have not lost a friend I so much valued. After what your letter expresses, I shall not need to say any thing to justify myself to you. I shall always think your own reflection on my carriage, both to you and all mankind, will sufficiently do that. Instead of that, give me leave to assure you that I am more ready to forgive you than you can be to desire it; and I do it so freely and fully, that I wish for nothing more than the opportunity to convince you that I truly love and esteem you, and that I have the same good-will for you as if nothing of this had happened. To confirm this to you more fully, I should be glad to meet you any where, and the rather, because the conclusion of your letter makes me apprehend it would not be wholly useless to you. But whether you think it fit or not, I leave wholly to you. I shall always be ready to serve you to my utmost, in any way you shall like, and shall only need your commands or permission to do it.

“My book is going to press for a second edition; and, though I can answer for the design with which I write it, yet, since you have so opportunely given me notice of what you have said of it, I should take it as a favour if you would point out to me the places that gave occasion to that censure, that, by explaining myself better, I may avoid being mistaken by others, or unawares doing the least prejudice to truth or virtue. I am sure you are so much a friend to them both, that, were you none to me, I could expect this from you. But I cannot doubt but you would do a great deal more than this for my sake, who, after all, have all the concern of a friend for you, wish you extremely well, and am, without compliment, &c.”83

To this letter Newton made the following reply:—

“Sir,

“The last winter, by sleeping too often by my fire, I got an ill habit of sleeping; and a distemper, which this summer has been epidemical, put me farther out of order, so that when I wrote to you, I had not slept an hour a night for a fortnight together, and for five days together not a wink. I remember I wrote to you, but what I said of your book I remember not. If you please to send me a transcript of that passage, I will give you an account of it if I can.—I am your most humble servant,

“I^s. Newton.

“Cambridge, Oct. 5th, 1693.”

Although the first of these letters evinces the existence of a nervous irritability which could not fail to arise from want of appetite and of rest, yet it is obvious that its author was in the full possession of his mental powers. The answer of Mr. Locke, indeed, is written upon that supposition; and it deserves to be remarked, that Mr. Dugald Stewart, who first published a portion of these letters, never imagines for a moment that Newton was labouring under any mental alienation.

The opinion entertained by Laplace, that Newton devoted his attention to theology only in the latter part of his life, may be considered as deriving some countenance from the fact, that the celebrated general scholium at the end of the second edition of the Principia, published in 1713, did not appear in the first edition of that work. This argument has been ably controverted by Dr. J.C. Gregory of Edinburgh, on the authority of a manuscript of Newton, which seems to have been transmitted to his ancestor, Dr. David Gregory, between the years 1687 and 1698. This manuscript, which consists of twelve folio pages in Newton’s handwriting, contains, in the form of additions and scholia to some propositions in the third book of the Principia, an account of the opinions of the ancient philosophers on gravitation and motion, and on natural theology, with various quotations from their works. Attached to this manuscript are three very curious paragraphs. The first two appear to have been the original draught of the general scholium already referred to; and the third relates to the subject of an ethereal medium, respecting which he maintains an opinion diametrically opposite to that which he afterward published at the end of his Optics.84 The first paragraph expresses nearly the same ideas as some sentences in the scholium beginning “Deus summus est ens Æternum, infinitum, absolute perfectum;”85 and it is remarkable that the second paragraph is found only in the third edition of the Principia, which appeared in 1726, the year before Newton’s death.

In the middle of the year 1694, about the time when our author is said to be beginning to understand the Principia, we find him occupied with the difficult and profound subject of the lunar theory. In order to procure observations for verifying the equations which he had deduced from the theory of gravity, he paid a visit to Flamstead, at the Royal Observatory of Greenwich, on the 1st September, 1694, when he received from him a series of lunar observations. On the 7th of October he wrote to Flamstead that he had compared the observations with his theory, and had satisfied himself that by both together “the moon’s theory may be reduced to a good degree of exactness, perhaps to the exactness of two or three minutes.” He wrote him again on the 24th October, and the correspondence was continued till 1698, Newton making constant application for observations to compare with his theory of the planetary motions; while Flamstead, not sufficiently aware of the importance of the inquiry, received his requests as if they were idle intrusions in which the interests of science were but slightly concerned.86

In reviewing the details which we have now given respecting the health and occupations of Newton from the beginning of 1692 till 1695, it is impossible to draw any other conclusion than that he possessed a sound mind, and was perfectly capable of carrying on his mathematical, his metaphysical, and his astronomical inquiries. His friend and admirer, Mr. Pepys, residing within fifty miles of Cambridge, had never heard of his being attacked with any illness till he inferred it from the letter to himself written in September, 1693. Mr. Millington, who lived in the same university, had been equally unacquainted with any such attack, and, after a personal interview with Newton, for the express purpose of ascertaining the state of his health, he assures Mr. Pepys “that he is very well,—that he fears he is under some small degree of melancholy, but that there is no reason to suspect that it hath at all touched his understanding.”

During this period of bodily indisposition, his mind, though in a state of nervous irritability, and disturbed by want of rest, was capable of putting forth its highest powers. At the request of Dr. Wallis he drew up an example of one of his propositions on the quadrature of curves in second fluxions. He composed, at the desire of Dr. Bentley, his profound and beautiful letters on the existence of the Deity. He was requested by Locke to reconsider his opinions on the subject of innate ideas; and we find him grappling with the difficulties of the lunar theory.

But with all these proofs of a vigorous mind, a diminution of his mental powers has been rashly inferred from the cessation of his great discoveries, and from his unwillingness to enter upon new investigations. The facts, however, here assumed are as incorrect as the inference which is drawn from them. The ambition of fame is a youthful passion, which is softened, if not subdued, by age. Success diminishes its ardour, and early pre-eminence often extinguishes it. Before the middle period of life Newton was invested with all the insignia of immortality; but endowed with a native humility of mind, and animated with those hopes which teach us to form an humble estimate of human greatness, he was satisfied with the laurels which he had won, and he sought only to perfect and complete his labours. His mind was principally bent on the improvement of the Principia; but he occasionally diverged into new fields of scientific research,—he solved problems of great difficulty which had been proposed to try his strength,—and he devoted much of his time to profound inquiries in chronology and in theological literature.

The powers of his mind were therefore in full requisition; and, when we consider that he was called to the discharge of high official functions which forced him into public life, and compelled him to direct his genius into new channels, we can scarcely be surprised that he ceased to produce any original works on abstract science. In the direction of the affairs of the mint, and of the Royal Society, to which we shall now follow him, he found ample occupation for his time; while the leisure of his declining years was devoted to those exalted studies in which philosophy yields to the supremacy of faith, and hope administers to the aspirations of genius.