Why do we write?!

I wonder why do we write? What is the purpose of writing? Have you ever noticed people who cannot express their feelings? Have you ever been in a situation that you wish to recall a proper word to describe an action to group of friend/people. You say: I know the word; it is right on my tongue!
I believe writing is a great practice to improve someone's ability to express his/her feelings. Many times I have lost my ability to express a meaning to someone! However, I have noticed writing provides a practice to improve my ability to communicate with other. Keeps me updated of language abilities and use of words without getting angery.
I believe people who are getting angry and use profanity are the ones who can not express themselves as well as their feelings, properly.
I recall when I was going to university we had a professor in machine design course who made us to explain every design we did in essay type of answers. It was quite difficult at the beginning for me. I had come from a country, which no value was given to essay writing in many aspects (I tend to believe you’d agree with me:-).
I recall that professor went on once, because of tremendous objective he was receiving to his methodology, by saying, “imagine you are a best engineer ever and you have designed many items needed by people around you. You are an excellent engineer with ability of Albert Einstein when it comes to calculation of nonlinear systems! But imagine you can't express all those wonderful innovations of yours to the public!! How would you ever make people aware of your invention? How are you going to make money out of those inventions?" After carefully listening to those words, I concluded that writing is a tool that we all should be equipped with!
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And rain keeps coming and coming in Tehran!!!... Like energizer battery keeps going and going!!:-)
I have no car to go home this afternoon, so I will be one of those pedestrians who should hid from fast drivers!!:-)