When I was about 8, I voraciously devoured every Enid Blyton school story I could get my hands on. Literally. The covers were gnawed off almost obsessively. Folds were made that marked the boundaries of which bit would be torn off that day. By the time I was 11, I looked back on this habit with loathing and gave out mini codes of conduct with every paperback I lent, so that they would return to me pristine and unsullied by the grubby hands of my excessively carefree friends. My brother is still regularly made to suffer for sitting on The Complete Sherlock Holmes (a Christmas present) and bending the cover irreparably. I would never, ever, ever have dreamed of actually writing in any of my books.
However, I’ve found more recently that the increasingly poor editing of (specifically, but I doubt exclusively) certain ancient history books has led to me read with a pen (yes, my children, a PEN) to hand in order to correct errors. You might be marvelling at my unbounded hubris, but let me show you what I mean (errors coloured green):