Comment by thesz

https://www.youtube.com/watch?v=8kUQWuK1L4w

APL inventor says that he was developing not a programming language, but notation to express as much problems as one can. He found that expressing more and more problems with the notation first made notation grow, then notation size started to shrink.

To develop conceptual knowledge (when one's "notation" starts to shrink) one has to have some good memory (re-expressing more and more problems).