All I sure about is my own ignorance.
Theology, Math, Physics, Philosophy, Poetry, Opera, (most forms of music), languages, Orations, Planes, Chemistry, Microbiology, Viralogy, Biochemistry, and basic anyway somthing works or how people think.
Melissa Scott and her study of the original Greek and Hebrew of the Bible
A Day In The Life Of Ivan Denisovich
The Bible, The Koran, Moby Dick, Pllgrims Progress, Paradise Lost, the trilogy of Inferno, Pugatoria, Paradisio, Ars Amoris, Ceasars Gaelic Commentaries to name just a few.