While I'm sure that deliberate summarization and also as a sibling posted, the slowness of the act are parts of it, I strongly suspect the actual mechanism of m

While I'm sure that deliberate summarization and also as a sibling posted, the slowness of the act are parts of it, I strongly suspect the actual mechanism of moving hand across space helps to engrave concepts in the mind. The connection between mind and body is strong. I can only speak to myself of course, but I've found that even quickly, absentmindedly, and imprecisely drawing out items on paper cements ideas in my mind way better than not doing it. I think the same concept applies to typing things out on a computer instead of copy and pasting. Even with minimal front-of-mind attention, the retention rate is stronger. Of course, writing on paper is even better than typing it on a computer. That being said, I wouldn't trade typing on a computer for writing on paper, given the sheer speed I can achieve with one. But if we're limiting ourselves to trying to better increase retention and understanding, then I think pen-on-paper is the most valuable thing one can do.