For any reasonably complex field of study, you'll eventually hit a point of diminishing returns on what you can learn further. You can keep figuring out new things, but it'll take more effort.
A lot of programmers brag that they can learn a new language in a day. That's only true if you squint enough. Getting the full use out of a language will take years of study. That's especially true of systems like LISP, Unix, and Euclidian Geometry, where the basic system is made of a few simple parts that combine in incrediably complex ways. It's easy to learn the basics of such a system, but the combinational explosion cannot be grasped so easily.
"There is no shame in being self-taught, only in not trying to learn in the first place." -- Atrus, Myst: The Book of D'ni.
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