Question 140·Medium·Central Ideas and Details
The following passage is from Clara E. Porter’s 1910 essay “On the Infinite Night.”
Look upward on a clear winter evening, and the sky seems strewn with careless handfuls of light.
Each point is a distant sun, unfathomably removed, yet it reaches us through the thin glass of the atmosphere and the even thinner glass of our certainty.
Instruments may count, classify, and even photograph these fires, but numbers cannot exhaust wonder.
The more faithfully the telescope delivers new worlds to our catalogs, the more keenly we feel the boundaries of our own.
Which statement best captures the central idea of the passage?
For central idea questions, read the full paragraph first and summarize the author’s overall message in your own words. Then eliminate choices that introduce topics not present in the passage or that focus on only one detail (like a single example) instead of the author’s broader point. Finally, pick the option that matches the passage’s main emphasis and scope.
Hints
Focus on the overall message, not small details
Ask yourself: After reading this paragraph, what big idea does the author want you to take away about looking at the night sky?
Pay attention to the beginning and the end
Reread the first sentence and the last sentence. How does the description of the sky at the start connect to the idea of “boundaries” at the end?
Think about what tools can and cannot do
The passage mentions instruments and telescopes. Is the author mainly praising these tools, or pointing out something they cannot fully capture?
Step-by-step Explanation
Identify the passage’s main focus
Read the whole paragraph and ask: What is the author mainly talking about?
The passage doesn’t describe navigation, city light pollution, or the technical workings of astronomy. Instead, it reflects on what it means to look at the night sky and what that experience suggests about us as observers.
Notice key descriptive phrases
Look closely at the important phrases:
- “Each point is a distant sun, unfathomably removed” — emphasizes immense distance and scale.
- “the thin glass of the atmosphere and the even thinner glass of our certainty” — suggests human knowledge is fragile/limited.
- “Instruments may count, classify… but numbers cannot exhaust wonder” — measurement can’t fully capture meaning or mystery.
- “The more faithfully the telescope delivers new worlds… the more keenly we feel the boundaries of our own” — learning more can make our limits feel clearer.
Turn the observations into a central idea
Put the clues together:
- The sky points to a universe that is enormous and hard to fully grasp.
- At the same time, the author stresses that tools and numbers cannot fully contain what we see, and that our certainty has boundaries.
So the central idea combines cosmic vastness with the limits of human understanding.
Select the option that matches both parts of the central idea
Evaluate the choices:
- The option about ancient sailors and navigation introduces a topic not mentioned.
- The option about astronomy depending primarily on telescopes narrows the passage to technology, but the author emphasizes what tools cannot fully capture.
- The option about city lights and appreciation introduces an outside issue not discussed.
- The remaining option matches both key parts: the universe’s vastness and the limits of human understanding.
Therefore, the correct answer is The night sky shows the universe’s vastness and also the limits of human understanding.