So I think we have to put something more than randomness and following links to use here. (You can spend a lot of time learning about a big system like Linux without hitting many of the most important ideas in computing -- so we have to heed the "Art is long and Life is short" idea.
Part of the "Oxbridge" process is to have a "reader" (a person who helps you choose what to look at), and these people are worth their weight in gold ...