Mr Aiscough had given Sir Isaac before he sett out for Cambridge Sanderson's logick & told him that was the first book his tutor would read to him, this Sir I. read over by himself & when he came to hear his tutor's lectures upon it found he knew more of it than his tutour, who finding him so forward told him he was going to read Kepler's Opticks to some gentlemen commoners <1v> & that he might come to those lectures. Sir I immediately read it at home & when his tutour gave him notice of the lectures he told him he had already read that book through He bought a book of Iudicial Astrology out of a *[1] curiosity to see what there was in that science & read in it till he came to a figure of the heavens which he could not understand for want of being acquainted with Trigonometry, & to understand the ground of that bought an English Euclid with an Index of all the problems at the end of it & only turned to two or three which he thought necessary for his purpose & read nothing but the titles of them finding them so easy & self evident that he wondered any body would be at the pains of writing a demonstration of them & laid Euclid aside as a trifling book, & was soon convinced of the vanity & emptiness of the pretended science of Iudicial astrology


About Midsummer 1664 he read Oughtred's Clavis which he understood though not entirely he having some difficulties about what the author calls scala secundi et tertij gradus relating to the solution of Quadratick cubic Æquations – * < insertion from the right column > * The opinion he had of Oughtred's Clavis appears by the following memorandum found among his papers in his own writing & signed with his name viz –

Mr Oughtred's Clavis being one of the best as well as one of the first Essays for reviving the Art of Geometrical Resolution & Composition – I agree with the Oxford professors that a correct edition thereof to make it more usefull & bring it into more hands will be both for the honour of our nation & advantage of Mathematicks —

< text from f 2v resumes >

He then young as he was took in hand Des-Cartes's Geometry (that book which Descartes in his Epistles with a sort of defiance says is so difficult to understand) * < insertion from the right column > * he began with the most crabbed studies & books (like a high spirited horse who must be first broke in plowed grounds & the roughest & steepest ways or could otherwise be kept within no bounds < text from f 2v resumes >

When he had read two or three pages <3r> & could understand no farther he being too reserved or modest to trouble any person to instruct him began again & got over three or four more till he came to another difficult place, & then began again & advanced farther & continued so doing till he not only made himself master of the whole without having the least light or instruction from any body but discovered the errors of Descartes, as appears by the original book which he read <3v> at that time & is still in being & marked in many places in his own hand writing with these words Error – Error non est Geom.

< insertion from the right column >

< text from f 3v resumes >

Memorandum Mr Professor Smith told me he had seen the book it will be proper to mark the passages & shew they are errours

Soon after he stood to be a Scholar of the House & Dr Barrow examined him in Euclid which he knew so little of that Dr Barrow conceived a very indifferent opinion of him <4r> The Doctor never asked him about Descartes's Geometry not imagining that any one could be master of that book without first reading Euclid & Sir Isaac was too modest to mention it himself so that he was not made Scholar of the House till the year following

Upon this Sir I. read Euclid over again & began to change his opinion of him when he read that Parallellograms upon the same base & between the same parallells are equal & that other proposition that in a right angled triangle the square of the Hypothonuse is equal to the squares of the two other sides * < insertion from the right column > * & in his latter days he spoke with regret of his mistake at the beginning of his Mathematical Studies in applying himself to the works of Descartes & other Algebraic writers before he had considered the Elements of Euclid with that attention which so excellent a writer deserved – Pemberton in the preface < text from f 4r resumes >


About Christmas 1664 He read Shooten's miscellanies & Dr Wallis's Arithmetica Infinitorum & on the occasion of a certain interpolation for the quadrature of the circle found that admirable Theorem for raising a binomial to a power given, but before that time a little after reading Des Cartes's Geometry wrote many things concerning the vortices Axes Diameters of curves which afterwards gaue rise to that excellent tract de Curvis secundi generis & made several notes & remarks on Shooten's miscellanies which are still in being, that was his usual method in all the books he read — ——

Memorandum here follows what is writt by Mr Iones, at least must be disposed with it in proper places –

In the winter between the years 1664 & 1665 he found the method of infinite series, & in summer 1665 being forced from Cambridge by the plague computed the area of the Hyperbola at Boothby in Lincolnshire to two & fifty figures by the same method –

Memorandum – This is writt in a pocket book in Sir I.'s own hand writing


In August 1665 Sir I. bought a prism at Sturbridge fair to try some experiments upon Descartes's book of colours [2] & when he came home & made a small hole in his window shutter & darkened the room & placed his prism between that & the wall he found instead of a circle the light made an oblong form with semi circular ends &c which convinced him of the falsity of Descartes's Hypothesis of Colours <5v> & he then found out his own Theory though he could not demonstrate it for want of another prism for which (with a patience much to be admired in so new & engaging a discovery) he staid till next Sturbridge Fair & then proved what he had before found out — * < insertion from the right column > X Thus Truth as it often happens arose out of those errors which gave occasion to the inquiries by which themselves were detected.

< text from f 5v resumes >

In the year [3] he retired again from Cambridge on account of the plague to his mother in Lincolnshire & whilst he was musing in a garden it came <6r> into his thought that the same power of gravity (which made an apple fall from the tree to the ground) was not limited to a certain distance from the earth but must extend much farther than was usually thought – Why not as high as the Moon said he to himself & if so that must influence her motion & perhaps retain her in her orbit, whereupon he fell a calculating what would be the effect of that supposition but being absent from books & taking the common estimate in use among Geographers & our sea men before Norwood <6v> had measured the earth, that 60 English miles were contained in one degree of latitude his computation did not agree with his Theory & inclined him then to entertain a notion that together with the power of gravity there might be a mixture of that force which the moon would have if it was carried along in a vortex, but when the Tract of Picard of the measure of the earth came out shewing that a degree was about 6912 English miles <7r> He began his calculation a new & found it perfectly agreable to his Theory –

See Pemberton's account of this particular in his preface who says there that it was a letter from Hook which put Sir I. upon recalculating & that letter Du Moivre says was not writt till 1673 – the difference may be ascertained by examining when Picard's book came out — * < insertion from the right column > * Generally Often the whole life of those who should make new discoveries is spent in learning only what is already found out but Sir Isaac # < text from f 7r resumes > # Having read only the few books already mentioned some of which rather led him into errors, <7v> & without the least help or instruction from any person he laid the foundation of all his discoveries before hee was 24 years old * < insertion from the right column > He had run over |  made himself master subdued all Nature at an age when even the Cesars in learning were but just setting out | beginning their conquests – & must call to every one's mind that passage in Iob. 32. c. 7. verse – I said days should speak & multitude of years should teach wisdom, but there is a spirit in man & the inspiration of the Almighty giveth them understanding

< text from f 7v resumes >

When he was in the warmest pursuit of his discoveries he going out left a candle on his table amongst his papers & meeting somebody who diverted him from returning as he intended , the candle sett fire to his papers & upon my asking <8r> him wether they related to his opticks or the method of Fluxions – he said to both & that he was forced to work them all over again – he had also writt a piece of Chymistry explaining the principles of that mysterious art upon experimental & mathematical proof & valued it much but it was unluckily burnt in his laboratory which casually took fire, & he would never undertake that work again – Nor is there any compleat treatise on this subject <8v> amongst his papers though there are several volumes in his own hand writing which are cheifly extracts out of Chymical authors Nor is it to be thought he spent so many hours in that study without producing some more regular & larger treatise upon it, than the Queries at the end of the Opticks which are certainly the result of long labour & study & contain a fund of Philosophy which will employ the learned world for many centuries

[1] * (which Hobbes calls the mother of all Philosophy) – Human nature – p. 112 –

[2] Memorandum Sir I. in the Philosophical transactions – 1. Vol. {Cowlturp} p. 128 – says it was 1666 – but in the same page he mentions using 2 prisms which he told me he did not buy the 2d till the year following – NB. he does not name Descartes but calls his book the celebrated Phænomena of colours

[3] Memorandum he says so p. 296 Phil. Tran. Abrid. p. 196 –

© 2024 The Newton Project

Professor Rob Iliffe
Director, AHRC Newton Papers Project

Scott Mandelbrote,
Fellow & Perne librarian, Peterhouse, Cambridge

Faculty of History, George Street, Oxford, OX1 2RL - newtonproject@history.ox.ac.uk

Privacy Statement

  • University of Oxford
  • Arts and Humanities Research Council
  • JISC