@yeghor, your take on function theory, does it seem elegant or beautiful to you? I'm asking because I've read that one way the brain decides on what's "true" is by seeing it as beautiful. Like a mathematical proof is sometimes described as beautiful or elegant when it seems to fit in all the right places. It's one of the brain's shortcuts to decision-making. But that element of beauty makes a theory that much more difficult to objectively examine for flaws. I've been there--where a theory of mine was so beautiful to me that I didn't want to let it go, even though I could see that it wasn't fitting with all of the information I had gathered. So, I've found it's good practice to leave room for doubt in all of my theories and to constantly look to see if I'm hanging on to them too tightly because they make sense or are beautiful, but only to me.