We may have noticed the phenomenon that great writers are often inspired by former writers, and literature doesn't belong to one person or a group of people, but to the coalition of literati. Together with their observations of the societies they lived in as witnesses, they put their inspirations into their works, which also became the inspirations of later writers. In other words, writers bear the roles of witness, readers and writers at the same time. In this essay, four groups of writers will be presented to illustrate the shift of the three roles.