The king decided to base the shapes of the consonants on the shape of the mouth, tongue, and teeth when each sound was made. For example, the letter mi-eum (ㅁ) looks like the mouth when making an "em" sound. Ni-eun (ㄴ) looks like a raised tongue when making an "en" sound. Ki-yeok (ㄱ) looks like the tongue when making a "guh" sound.