[tvanantwerp]

I can't say what the author's intent was, but I see two ways to parse this: one I disagree with, one I agree with.

The disagreeable interpretation is that the only way to learn is from a pristine book. This is so obviously stupid that I see no reason to discuss it further.

The other interpretation, which I think is more useful but unclear from the text, is that _passive activities are subpar learning activities_. From what I've read of effective studying techniques, things like highlighting text don't help. Active recall techniques like spaced repetition are much more useful for cementing learned knowledge. Likewise, if you're "learning" from a screen by just staring at it, consuming it, then your knowledge-to-inputs ratio is going to be low. I've watched plenty of YouTube videos on how to do numerous things, but I couldn't do any of them on the spot because I've never tried. The knowledge went in one ear and out the other. The material must be engaged with somehow.

[sockaddr]

> The disagreeable interpretation is that the only way to learn is from a pristine book. This is so obviously stupid that I see no reason to discuss it further.

Agreed. I actually prefer to see markings in used books I'm reading. Not only does it provide possibly useful context into how another person is thinking about the topic, but it even makes it feel like there's a bit of friendship or community in the book.

[zaphar]

highlighting and underlining don't per-se cause you to learn. However they do have two useful properties.

1. The act of looking for and underlining or highlighting text helps you to focus on identifying core ideas or concepts in the text.

2. Underlined and highlighted text are useful as hints when reviewing a text and reviewing a text is a critical part of learning.

These properties are so helpful that many texts actively help you to absorb their content by bolding, underlining, or otherwise calling attention to core concepts and ideas for you.