By external knowledge, do you mean knowing how the program you're using works?

the point of the GUI is that folks can intuit how a program works without having to be versed in how it works.

	▲	fwip 18 hours ago \| parent [-]
		Okay. For what it's worth, vim tells you that you can type :help to get help every time you start it up. It would take a while until you got to the section about the file tree, though.