Symbolism is not used in the book, Literary Theory: An Introduction. The author does, however, note, that the study of aesthetics resulted in the changing position of the artist, who was no longer elevated socially by being in the service of an aristocrat or ruler. Thus, the renewed interest in aesthetics led to the doctrine of the symbol, which became dominant in literary tradition. Symbolism provided a way to react to the dominant philosophies of the day in a radical way. The symbol allowed the writer to transcend spiritual truth and directly oppose to the philosophies of the period (19th century).
Literary Theory: An Introduction