Newton’s youthful interest in learning was encouraged by his uncle, William Ayscough, and by the schoolmaster at Grantham, John Stokes. Despite opposition from his mother, who wanted him to stay at home and farm, Newton was admitted to Trinity College, Cambridge, on 5 June 1661, and matriculated on 8 July. His uncle had been educated at Trinity and one of the fellows of the College, Humphrey Babington, was related to a family with whom Newton had lodged while at school in Grantham. Perhaps because of some reluctance of his mother’s to waste money on education, perhaps in order to assist Babington, Newton entered Trinity as a sub-sizar, that is a student who was to supplement his income by acting as a servant either for the fellows or for other wealthier students, and who was allowed to pay lower fees for attending lectures.

Although this is not the earliest of Newton’s surviving notebooks, it may well be the one that he purchased, together with some ink, on his arrival in Cambridge. Undergraduate education at this time consisted largely of following courses of reading directed by a tutor, in Newton’s case Benjamin Pulleyn. These initially focussed on the traditional skills of grammar, logic, and rhetoric. At Cambridge, it was also usual for undergraduates to study ethics, metaphysics, physics, and mathematics. Together with some books that he bought in the early 1660s, this notebook bears witness to Newton’s first steps in the Aristotelian curriculum of the early modern university. It is dated on the flyleaf, ‘Isaac Newton/ Trin: Coll Cant/ 1661’, and contains notes and occasional exercises relating to Newton’s reading, compiled in the manner of summarising and glossing recommended by most tutors. Many of these notes are written in the rather crude form of secretary hand that the young Newton practised. They cover his study of Aristotle’s Organon and Porphyry’s Isagoge; the scholastic compendium, Physiologiae peripateticae, by Joannes Magirus; Aristotle’s Ethics and the Ethica of Eustachius of St Paul; the Axiomata of Daniel Stahl, which introduced him to Aristotelian metaphysics, and, finally, a text-book of rhetoric by the great humanist scholar, Gerardus Joannes Vossius

By about the beginning of 1664, Newton’s writing had matured into the neat, if slightly spindly, italic hand that he would continue to develop over the rest of his life. His reading and thinking had also taken a new course, albeit one that was promoted by many of the best tutors in contemporary Cambridge. Newton had begun to reflect for himself on the metaphysical and natural philosophical terms and concepts deployed by the scholastic authors that he had been studying. Prompted perhaps by the scholarship to which he was elected in April 1664, Newton had started to read for himself both in the classical sources and commentaries and in contemporary philosophical and scientific writing, notably the works of Walter Charleton and René Descartes. Within the confines of a traditional commonplace book, and deploying many of the categories of renaissance philosophy, Newton had thus embarked through reading on his career as a mechanical, and eventually experimental, philosopher. Quoting portentously from Charleton, he headed his remarks ‘Amicus Plato amicus Aristoteles magis amica veritas’ (Plato is my friend, Aristotle is my friend, but my greatest friend is truth).

Among the works of the new philosophy with which Newton became acquainted were several dealing with comets. The observation and study of comets was important for natural philosophers since their motion raised questions about the orderly structure of the heavens and the relationship between celestial and terrestrial matter. A list of books that Newton made at the back of this notebook included several of the works that had helped to make the study of comets controversial, notably the Descriptio cometae (Leiden, 1619) of the Dutch mathematician, Willebrord Snell, which had analysed the comet of winter 1618–19, as well as tracts by William, Landgrave of Hesse-Cassel, on the comet of 1585, and by the Copernican astronomer, Christopher Rothmann. Newton transcribed tables of the motion of the comets of 1585 and 1618 from Snell. He also noted the appearance of a comet in early December 1664, going on to describe his own observations ‘On fryday before midnight Decembr. 23d 1664’.

The pages that are displayed show Newton’s continued observations of the comet on 24, 27, 28, 29, and 30 December 1664 and between 1 and 23 January 1665. They include a diagram to illustrate the relative position of the comet with reference to the location of the stars, for which Newton based himself on Vincent Wing’s publication (1651) of the catalogue of Tycho Brahe. Newton’s descriptions of the comet were not always clear, and his initial attempt to track its movements by comparison with those of the moon displayed his ignorance of the limits of contemporary astronomical knowledge. But the excitement of seeing for the first time ‘a Comet whose rays were round her, yet her tayle extended it selfe a little towards [the] east’ was clear. Newton had seen with his own eyes that the Aristotelian distinction between comets with rays and comets with tails could not be sustained. Through his reading of Descartes, Newton was also aware of contemporary ideas that the appearance of the comet’s tail might simply be an optical phenomenon. He had realised the potential of comets as exemplars of celestial motion. Yet, although his observations proved to be reliable, there is little evidence that Newton’s early interest in comets was sustained. He made a few further notes on a new comet in 1665 but seems not to have been concerned by the dispute between the French astronomer Adrien Auzout and his rival from Danzig, Johannes Hevelius, over their observation of the comets of 1664 and 1665.

J.E. McGuire and Martin Tamny (eds), Certain Philosophical Questions: Newton’s Trinity Notebook (Cambridge, 1983), especially pp. 296–304; A. Rupert Hall, ‘Sir Isaac Newton’s Note-book, 1661–1665’, The Cambridge Historical Journal, 9 (1948), 239–50; D.E. Smith, ‘Two Unpublished Documents of Sir Isaac Newton’, in W.J. Greenstreet (ed.), Isaac Newton 1642–1727 (London, 1927), pp. 16–34; Richard S. Westfall, Never at Rest. A Biography of Isaac Newton (Cambridge, 1980), pp. 66–104; William T. Costello, SJ, The Scholastic Curriculum at Early Seventeenth-Century Cambridge (Cambridge, Mass., 1958); Tabitta van Nouhuys, The Age of Two-Faced Janus (Leiden, 1998); Gary W. Kronk, Cometography, volume 1 (Cambridge, 1999), pp. 350–7.

Assessed ‘Not fit to be printed’ on behalf of Newton’s executors by Thomas Pellet (25 September 1727); presented to Cambridge University Library by the fifth Earl of Portsmouth. See A Catalogue of the Portsmouth Collection of Books and Papers written by or belonging to Sir Isaac Newton (Cambridge, 1888), p. 47. Exhibited in 1987: ‘The Making of Newton’s “Principia” (1664–1687)’, case 1, items 1–3.