For a few years at the beginning of my PhD, when I typed 'f' into the URL bar of my browser, www.feynmanlectures.caltech.edu/III_toc.html was the autocomplete i

For a few years at the beginning of my PhD, when I typed 'f' into the URL bar of my browser, www.feynmanlectures.caltech.edu/III_toc.html was the autocomplete instead of www.facebook.com. They are genuinely amazing once you have already studied some physics because they are so basic, yet so deep.