I GOT a real thrill in December 1999 in the Reading Room of the Morgan Library in New York when the librarian, Sylvie Merian, brought me, after I had completed an application with a letter of reference and a photo ID, the first, oldest notebook of Isaac Newton. First I was required to study a microfilm version. There followed a certain amount of appropriate pomp. The notebook was lifted from a blue cloth drop-spine box and laid on a special padded stand. I was struck by how impossibly tiny it was — 58 leaves bound in vellum, just 2 3/4 inches wide, half the size I would have guessed from the enlarged microfilm images. There was his name, “Isacus Newton,” proudly inscribed by the 17-year-old with his quill, and the date, 1659.