having hit, finally and too late, on 'symbolic' as the word I needed when talking to a few classes about the words 'analog' and 'digital', thought of my favorite volume of Knuth, Seminumerical Algorithms, next to other lucky books on computation. so literal when thinking of desert-island books, as when I play imagine my bed is adrift at sea. SA I wouldn't stop to use a machine, maybe writing to derive some expression, but not moving away farther as part of reading it, like I would in say Introduction to the Coriolis Force, or Microcomputer Quantum Mechanics. or more, would think I ought to. the image of how to use differs. in ICF and MQM the machine is next to the book in one hand, looking back and forth, not just to transcribe long programs. or if not quite, there's Knuth in both hands, and carried for reading, and lying down too. he's got a computer existing only (or in the future: most) in his book.
the useful thing for me was to arrange books by this quality, some have more or less, and to think I'd like to be towards a side, or place (a bit above,)(because it makes more than a line) with writing

a strip?width, hairline with/or-w/o graduations. could graduations disappear and give width (and be that way equivalent?). [a fog of red-brown color of tea cup is here in width-talk], and irregular gradations could give in change a particular kind of width? [red brown cloth book binding I am surprised remember cutting and gluing, folding stapling]