‘Because the speech of this country is different from that of China, it does not match the [Chinese] letters. Therefore, even if the ignorant want to communicate, many of them in the end cannot state their concerns. Saddened by this, I have 28 letters newly made. It is my wish that all the people may easily learn these letters and that be convenient for daily use.’
(Sejong the Great)
I'm really impressed by both the letters and King Sejong's reign, and actually if it wasn't for him I wouldn't be studying Korean rigth now. For more about the subject of hangeul see this or in case of TLDR watch Tree With Deep Roots which is almost entirely fiction but anyways it's fun.
* the Korean kingdom's name at the time
Egyszer volt, hol nem volt, volt egyszer egy nagy király Joseonban*, aki szerette volna, ha minden alattvalója tudna írni és olvasni...
...ezért megalkotta a legjobb ábécét.
*Korea korabeli neve
További információ a témáról: hangül, Wikipédia