How does the author use flashback in the novel, Nights When Nothing Happened?

In Chapter Four, Liang has a flashback about his mother's death, because of which, we come to understand that she died when he was very young. After his mother's death, his father told him that she left them to go live on the moon (and that this was Liang's fault). Consequently, Liang would often look at the moon and think about his mother. As he walks home drunk from the poker game in Chapter Four, he looks in the sky for the moon and then contemplates his belief that his family will one day leave him, just as his mother did.