Once, being called upon in class to recite from Euclid, he declined and shocked the professor by saying, "It is a trifling book--I have mastered it and thrown it aside." And it was no idle boast--he knew the book as the professor did not. When he arrived at Cambridge, he carried in his box a copy of Sanderson's Logic presented to him by his uncle--the uncle having no use for it. It happened to be one of the textbooks in use at Trinity. When Isaac heard lectures on Sanderson he found he knew the book a deal better than the tutor, a thing the tutor shortly acknowledged before the class. This caused young Mr. Newton to stand out as a prodigy. Usually students have to rap for admittance to the higher classes, but now the teachers came and sought him out. One professor told him he was about to take up Kepler's Optics with some post-graduate students--would young Mr. Newton come in? Isaac begged to be excused until he could examine the book. The volume was loaned to him. He tore the vitals out of it and digested them. When the lectures began, he declined to go because he had mastered the subject as far as Kepler carried it.
Genius seems to consist in the ability to concentrate your rays and focus them on one point. Isaac Newton could do it. "On a Winter day I took a small glass and so centered the sun's rays that I burned a hole in my coat," he wrote in his subsizar journal.
The youth possessed an imperturbable coolness: he talked little, but when he spoke it was very frankly and honestly. From any other his words would have had a presumptuous and boastful sound. As it was he was respected and beloved. At Cambridge his face and features commended him: he looked like another Cambridge man, one Milton--John Milton--only his face was a little more stern in its expression than that of the author of "Paradise Lost."
In two years' time Isaac Newton was a scholar of whom all Cambridge knew. He had prepared able essays on the squaring of curved and crooked lines, on errors in grinding lenses and the methods of rectifying them, and in the extraction of roots where the cubes were imperfect: he had done things never before attempted by his teachers. When they called upon him to recite, it was only for the purpose of explaining truths which they had not mastered.