Kim Si-seup's ancestors originally came from Gangneung, Gangwon-do, but Kim himself was born in Seoul. Throughout his life, Kim Si-seup (???) maintained a special bond with the Gangwon area and compiled a book of poetry called Tangyugwandongnok which was based on family history and experiences he had in the area. Kim was an extremely gifted child and had picked up reading ability at eight months of age. At five years of age, he was able to read and comprehend 'The Great Learning' and the 'Doctrine of the Mean'. Kim was a devout Buddhist and at twenty-one years of age he decided to leave government service and become a priest.