Once in a while, I pop into this site. This is the most amazing place of all at Cambridge University. It holds the largest and most important collection of Isaac Newton. They have digitised most of his work and you can spend a ton of time, browsing what the master wrote. You are actually seeing, as much as one can, what he actually did himself, wrote on his notebooks.
Some examples from his waste book. for his notes.
Some of his early papers
Gives me a serious shiver down the spine to observe these pages. Wonderful, what a brain.