Many languages have their own way of expressing the sounds they use in communication. In many cases, they borrow letters from other countries or develop them with time. A few peoples have invented their own writing system. Since I am a Korean, I am going to talk a little bit about the Korean writing system called 'Hangul', which means 'Great Letters'. Long time ago, we koreans borrowed Chinese writing system. Since spoken Korean differed much from spoken Chinese, only a limited number of elite group was able to read and write Korean.
About five hundred years ago, King Sejong the Great (the 4th monarch of the Lee Dynasty of the Choson Kingdom) ordered his scholars to devise a simple method of writing down spoken Korean so that even the people of lower class would be able to express their thoughts in writing. After years of studying, they invented and promulgated a simple writing system in 1443. The principles and method of devising those letters were very scientific and original.
After they invented Hangul, the king published a book about the purpose of the invention and about how to read the new writing system. The left picture is the first page of the book. It says, "The language of this country is different from that of China, so that it is impossible (for us Koreans) to communicate by means of Chinese characters. Therefore, among the unlearned people, there have been many who, having something to put into words, have in the end been unable to express themselves. Feeling sorry for this, I have newly made twenty-eight letters only because I wish them to be easy for everyone to learn and convenient for use in daily life....". (Translated by Shin, SangSoon, Professor Emeritus of Chonnam Nat'l University)
The picture is a mixture of Hangul and Chinese characters since he needed Chinese characters to tell people what the new letters meant and how they are pronounced. In the book, he continues to explain the individual symbols. With consonant symbols, he takes the initial or final sound of Chinese words to show them how each symbol is pronounced. He also takes the middle sound of certain Chinese words to explain each vowel symbol.