To read, I need a book and a pencil.
I’d like to emphasis that the pencil is as much a conduit of information between book and mind, as are eyes and brain, and as much of a physical necessity, as is my ability to hold a book open or flip a page.
I produce the following anecdotal evidence:
If I sink into a sofa with a book, but without a pencil, I will exhibit all the symptoms of anxiety and discomfort—fidgeting, gazing about, scratching, gazing about, back-and-forth page-flipping because I can’t remember what I just read, and some more gazing about—until I finally get up and acquire that writing implement I’d been gazing about for.
It has to be a pencil (preferably a mechanical pencil so I don’t need to sharpen it), but no erasers are needed.
Underlining is much maligned; it’s generally useless, it’s for those who can’t think at the time of reading but leave it for later, it produces an appearance of engagement while actually reducing it.
That is why I mark up the text and take notes.
Marking up a text involves: