Jeong Yak-jong
Jeong Yak-jong, also known as Augustine Chong, was a Korean Roman Catholic martyr who contributed greatly to the spread of Roman Catholicism in Korea. He was an older brother of Jeong Yak-yong and the father of Paul Chong Hasang. He wrote the first Catholic catechism using only Korean letters so that he could reach out to the common people as well as the nobles who were the only ones in Korean society who could read Chinese characters. He was first converted to Catholicism himself by Chinese priest Chou Wen-Mu.
