On what subject(s) are you an authority?

Rheumatoid arthritis because I have it, and I know how it affects my life.
Dyslexic because I deal with dyslexia, dysgraphia, and dyscalculia.
The Bible. I am reading it, and I want to understand God better.
Writing. For years I have researched and read books on how to write a novel.
If I have questions or want to understand a subject better, I read and research things.
Learning never ends.