The late Joel Feinberg‘s annotated copy of John Stuart Mill’s On Liberty has been digitally scanned and made publicly available through the Princeton University Digital Library. If you view the book on a touch screen you can flip through it quite naturally with a finger, as you would a book with very cooperative pages.
Princeton philosopher Michael Smith bought the book for a buck from Feinberg himself:
Feinberg’s copy of Mill’s essay came into the possession of Michael Smith when he was a visiting professor at the University of Arizona at Tucson in 2001. Feinberg, a long-time faculty member at Arizona, and his wife, Betty, had decided to move into a smaller home, so he sold off most of his philosophy library to faculty and students for one dollar per book, the proceeds going to the department. Smith saw On Liberty for sale and, assuming it was the copy Feinberg referred to while writing his masterwork The Moral Limits of the Criminal Law, bought it for sentimental reasons without opening it. Feinberg had plainly read and re-read his copy of Mill’s book many times, as it has been annotated using pencils, pens, and highlighters. Smith donated the book to the Princeton University Library in 2015.
It’s interesting to see some of Feinberg’s comments and indications of what he took to be important.
Also—and I mean no disrespect—it is kind of amusing to see how even one of the greats highlighted some pages in their entirety in that undergrad-ruins-a-book way:
The project is terrific, and it got me wondering about this question: if you could see one philosopher’s annotated copy of another philosopher’s work, which philosophers, and which book or article would it be?