Lewis, here, in Russian langauge, we distinguish / separate "humanitarian" sciences, "natural" and "precise" sciences.

It is a bit similar to English 'sciences' ("hard sciences" for what we call "precise") and 'humanities'. Difference is that, for a Russian 'history' is a science too. While some humanities might not be sciences at all. Idea is that... "humanitarian" sciences study things related to humans: language, for exmaple. It is produced by humans. Or history [of humans]. So "lingustics" is 'humanitarian" in our view.Accordingly students and people are divided here to "humanitarians" (a philologist) , "naturalists" (a biologist) "technic-ers" (an engineer). Phisicists and mathematicians stand somewhat above "technic-ers". Mostly division is "humanitarians" and "others". It is supposed that it defines your  mindset. If you graduated from a philological faculty you say about yourself "I'm a humanitarian" and by this you mean: "I'm afraid even to speak about intergrals and, God save, derivatives!"

It is a harmful distinction. I'm a 'multi-class' (in gamers terms) then: you wont' scare me with gauge theory or an ancient manuscript, both are just texts not easy to read which I CAN manage to understand if i work.
It is so much about limitations you put on your brain: not even attempting to think about certain things.
But it is ingrained in Russian students worldview:/

So why I'm telling this: once I asked myself if mathematics is "humanities" or "natural sciences"?
DOes it study the universe - or does it study a human?

 I absolutely love that last line you wrote there, Tia. This is the same Euler with the Euler-Bernoulli equation, I presume? Thank you for that link as well, I will definitely look into it before I sleep. I also like the word you used in your second paragraph: logically. This, I believe is where our limits as humans are apparent. Is it possible that, since mathematics is a logical way of problem-solving involving known and unknown (sometimes assumed as you mentioned), then our logic is not advanced enough to comprehend some of the most apparent mathematics in the universe?

Maths is never invented by any of human beings. It is more like a phenomenon, a natural scene that has been existing for many years long before the earth formed. 

Actually those kind of questions are helping the human being to think and get rid of the meaningless life, but sometimes it leads to skepticism in everything things because some of these questions are very sophisticated to answer

@Omar, but at the end of skepticism, won't there be a better understanding of things? After all, seeing is believing. @Jack, so we can/should treat it as cautiously as we would the discovery of nuclear fission?