Read the excerpt from "The Masque of the Red Death” by Edgar Allan Poe.

But these other apartments were densely crowded, and in them beat feverishly the heart of life. And the revel went whirlingly on, until at length there commenced the sounding of midnight upon the clock. And then the music ceased, as I have told; and the evolutions of the waltzers were quieted; and there was an uneasy cessation of all things as before. But now there were twelve strokes to be sounded by the bell of the clock; and thus it happened, perhaps, that more of thought crept, with more of time, into the meditations of the thoughtful among those who reveled. And thus, too, it happened, perhaps, that before the last echoes of the last chime had utterly sunk into silence, there were many individuals in the crowd who had found leisure to become aware of the presence of a masked figure which had arrested the attention of no single individual before. And the rumor of this new presence having spread itself whisperingly around, there arose at length from the whole company a buzz, or murmur, expressive of disapprobation and surprise—then, finally, of terror, of horror, and of disgust.

Based on the details in the excerpt, what is the primary purpose of this passage?