I've been reading a lot of library books lately, and have therefore been exposed to the marks and traces of other readers. The most amusing example I've found is above: this is the first page of F R Leavis's Mass Civilisation and Minority Culture, first published in 1930. I particularly like the fourth commentator, who either can't resist the temptation to instruct while insulting, or vice versa, and adheres to a high standard of punctuation even when writing graffiti. Mass Civilisation and Minority Culture is a short book and there is only one copy in my university library; it's therefore particularly heavily inscribed with other readers' marks. Paragraphs are underlined, starred, marked with arcane groupings of vertical lines and curly brackets, and key words are noted across the top of pages. Page corners are creased where they have been turned down. There is something ironic in this accumulation of evidence of mass readership on a text concerned with the preservation of a cultural elite.
In other books, readers have corrected typographical errors; one reader of a Delafield novel had carefully corrected the author's grammar. Unfortunately, their grasp of the use of the subjunctive was less sophisticated than EMD's, and the correction itself was wrong. Sometimes you get a sense of the reader's response through their marginalia, an exuberant "YES!" against a provocative statement or a bracing "Nonsense!". Changes in our sense of what is acceptable provokes readers to label racism and sexism where they encounter it.
I never, now, write or mark books, although I was encouraged to by previous English teachers: my A level copy of Keats is covered in pencil scribblings. Instead, I'm addicted to the use of page flags and post-its, which leave no trace for later readers. While I find it distracting when people have underlined bits of text - the eye is inevitably drawn to that sentence at the expense of others - the written annotations can be amusing, as above, and sometimes enlightening. They remind me that reading is not necessarily a solitary, individual activity, but can be a communal one, and that my understanding of a text draws inevitably on that of other readers, be they critics or marginal commentators.