It occurred to me that no one "self-educates", if what Charlotte Mason and GKC say about education is true. At the same time, everyone "self-educates". How is that so?
All education comes from without, in one sense. Education is what we learn, which essentially comes from how our mind and senses interact with the world. Reading a book is instruction/enlightenment etc from the author(s) of the book, the author is a teacher or guide in apprehending what he is writing about.
In another sense, no learning takes place unless the individual allows it in. Of course, it is very hard NOT to learn. Think about trying not to "learn" from a commercial on TV. Unless you mute it and turn your eyes away, it pours into your mind whether you like it or not (usually NOT).
Commercials are accessible to the extreme, like candy: pure sugar, food coloring and artificial flavoring. There is a paradox that learning we have to work for is more valuable; like digging gems out of the ground, or lifting weights. That doesn't mean that learning is more valuable when it is forced from outside; almost the opposite. But reading a book is harder work than watching TV, so reading is a better activity intellectually. Writing is harder work than reading; learning a language is extremely strenuous to the intellect.
Fun makes things easier again: everyone would rather play a song, play a football game, write something they enjoy writing, than do a drill or write on a boring assigned topic. Fun is the wrong word there, though; the word is MEANING. Those things are more "whole" and significant than isolated drills.
Fun is entertainment -- watching a football game, or listening to music, or reading fiction. Well, I'm still not quite there because these things are all passive physically, but potentially active aesthetically or imaginatively or whatever.
Back to my original thought, such as it was: education is possibly best thought of as an interaction between our own faculties and spirit and the outside world. That brings us to CM's analogy of food being presented and then taken, eaten and assimilated. We don't take sustenance from ourselves, as she said; we take it from outside but then make use of it according to our own capacities and will.