Final answer:
The section titled "only for a time" is an introductory overview that organizes central themes and prepares the reader for a detailed exploration of the topics in future discussions.
Step-by-step explanation:
The main idea of the section titled "only for a time" reflects a temporary exploration or introduction to more complex ideas that will be elaborated upon in future discussions. The sentence, "This sentence provides the main ideas of the essay and indicates the order in which they will be presented in the body paragraphs," suggests that the section organizes the central themes and sets a structure for the essay. In contrast, "The ideas presented in this section are but a glimpse into topics of modern physics that will be covered in much greater depth in later chapters," implies the section is a primer to more in-depth analysis. Lastly, "The moment described in this passage, and represented here, is not a narrative in the sense that the Last Judgment is, but it is rather a more esoteric concept of the Second Coming of Christ and the End of Time," reveals a focus on a symbolic or metaphorical event, rather than a literal storyline.