"So intent, so serious upon his studies that he ate very sparingly, nay, ofttimes he has forgot to eat at all, so that, going into his chamber, I have found his mess untouched, of which when I have reminded him he would reply, 'Have I?' and then making to the table, would eat a bit or two standing, for I cannot say I ever saw him sit at table by himself. At some seldom entertainments the masters of colleges were chiefly his guests.
"He very rarely went to bed till two or three of the clock, sometimes not till five or six, lying about four or five hours, especially at spring and fall of the leaf, at which times he used to employ about six weeks in his elaboratory, the fire scarcely going out either night or day, he sitting up one night, and I another, till he had finished his chemical experiments, in the performances of which he was the most accurate, strict, exact...."
When his most intense studies were carried on, "he learned to go to bed at twelve, finding by experience that if he exceeded that hour but a little, it did him more harm in his health than a whole day's study."
"He very rarely went to dine in the hall, except on some public days, and then if he has not been minded, would go very carelessly, with shoes down at heels, stockings untied, surplice on, and his head scarcely combed.... At some seldom times when he designed to dine in the hall, he would turn to the left hand and go out into the street, when making a stop when he found his mistake, would hastily turn back, and then sometimes, instead of going into the hall, would return to his chamber again.... In his chamber he walked so very much that you might have thought him to be educated at Athens, among the Aristotelian sect."
So absent-minded was he, the story is told of him, that going home to Colsterworth, he led his horse up a hill. When he designed to remount, the animal had slipped the bridle and gone away unperceived, though Newton held the bridle in his hand all the time. He would often sit down on his bedside after he rose, and remain there for hours without dressing, so completely absorbed was he in his thought. How few in all this world have been so devoted to science! And yet how many expect success without this devotion!