Kojŏn esŏ ch'ajŭn sŏrŭn ŭi sŏnggong, mahŭn ŭi chihye

Based on a famous saying by Confucius, "Achieve success in your 30's and obtain prudence in your 40's", this work shows how to glean wisdom from Chinese classics, in order to examine oneself regardless of one's age.