When i was young(er), i had the immense fortune of having a mentor, Dr. Fidel Antonio Alsina, who guided me into discovering the wonderful world of physics. His lessons (by letter at first and later, when he came to Barcelona, in person) were mostly centered on relativity, but there were lots of opportunities to talk about physics and epistemology as well. He taught me to keep an open and critic mind, and not to accept arguments on the grounds of authority alone: he was fond of remembering that Newton believed sunspots were windows used by the inhabitants of the Sun. But, at the same time, he warned me against becoming a crackpot (“sages are silly, but not that silly”), and to study hard and respectfully the writings of great physicists, like Newton himself. I remember Fidel recommended me reading Newton’s Queries at the end of his Optiks to get a glimpse of how Newton’s mind worked, an advice that i can’t but pass on to all of you with a serious interest in science. As it comes, i can do even better, and point you directly to the Questiones quaedam Philosophiae, which are available online as part of The Newton Project, an ambitious initiative to put online all of Newton’s manuscripts. A related project is The Chymistry of Isaac Newton, which is publishing Newton’s alchemical works. I’m not specially interested in the later, except for their publication of Newton’s most complete laboratory notebook, which includes many of his optics experiments. A great way of seeing a great mind in action.
If you have not yet read any biography of Newton, of course the canonical reference is Westfall’s awesome Never at Rest : A Biography of Isaac Newton, but let me also recommend (for those of you with less time in your hands, and a library at hand, since it seems to be out of press) Gale E. Christianson’s In the presence of the Creator: Isaac Newton and his times, a book i enjoyed immensely.