Final answer:
The passage introduces the book and its themes, and discusses the symbolism of white, grey, and green. Each detail in the passage helps shape the thematic topics.
Step-by-step explanation:
The passage mentions the book's title, author, setting, and narrator to provide a summary of the text. This summary sets the stage for the writer's main topic, which is the relationship between the setting and the main themes of the book. The writer then presents their specific thesis about the symbolism of white, grey, and green. Each detail in the passage shapes the thematic topics by providing background information and connecting them to the main argument of the text.