I would rather have questions that can't be answered than answers that can't be questioned. ~Richard Feynman
You may not know all the lectures are completely online:
Volume 1: feynmanlectures.caltech.edu/I_toc.html
Volume 2: feynmanlectures.caltech.edu/II_toc.html
Volume 3: feynmanlectures.caltech.edu/III_toc.html
