The book Sagar's Motto was written in the first half of13rd century. The author stated that the purpose of writing this book is: "In order to make the world have rules to follow, I will preach the holy law." As a religious scholar, he observed and commented on various social phenomena, and put forward a series of opinions on dealing with the world, learning, knowing people and treating things, which involved distinguishing between the wise and the foolish, promoting the good and restraining the evil, and converting to Buddhism. All aphorisms are written in the form of seven words and four sentences. From this book, we can not only get a glimpse of the writing art of Tibetan aphorisms and aphorisms, but also examine the social ideological trend, moral standards, religious consciousness, customs and habits of Tibetan serfdom society.