Some of the key symbols in the film “Dead Poets Society" include candles, snow, vomit and flags. They are visual evocations of some of the key themes of the movie, such as the importance of knowledge and the loss of innocence.
The movie opens in a dark room. Boys in prep school blazers huddle around a candle. They light it, and it casts a faint glow about the room. This moment is brief, but it is important: it symbolizes the accrual of knowledge that is to come. At the beginning of the movie, these boys are bathed in darkness, but there is still a flicker of hope.
Another symbol is a vast expanse of unblemished snow sullied by a puddle of vomit. The snow is pure and white: it represents innocence. The vomit represents the loss of innocence. The boys are reaching adulthood, and they are casting off the innocence of their childhoods.
Much of the visual rhetoric of the film works to establish the authoritarian atmosphere of the school. Visual symbols like flags help to assert the unimpeachable supremacy of the headmaster.