Aglaya finds Prince Myshkin asleep on the bench in the park. He tells her of the events of the preceding night and morning. He believes Hippolite wished to evoke people's respect and the feeling of regret of his death. Aglaya offers the prince her friendship and says his mind is of a higher kind, something no one around her, except her mother, understands. Then Aglaya announces that she has decided to run away from home, and she asks Myshkin to help her. After the prince calls the idea absurd, she asks how he dared write her a "love" letter. He replies that it was no such thing and that he merely wrote to her as to a light.
Aglaya tells Myshkin that she is in love with Ganya and that she promised to marry him during a recent meeting with him near this same bench in the park. She says that Ganya, in order to prove the strength of his love, has burned his finger. The prince catches Aglaya's lie, as he saw Ganya the day before and remembers that his hands were in perfect condition. Aglaya admits to lying. She then says that when she read the poem about the poor knight, she was hoping to show Myshkin that she knew everything about what happened between him and Nastassya Filippovna.
They begin talking about Nastassya Filippovna. Myshkin says he does not love the woman, although he did come to Pavlovsk because of her. Aglaya says that Nastassya Filippovna has been writing letters to her, and she gives the letters to Myshkin. Nastassya Filippovna wishes to see Aglaya and the prince marry, at which time she herself will marry Rogozhin right away. Suddenly Madame Yepanchin finds the two sitting on the bench. Aglaya runs off. Madame Yepanchin and the prince follow her to the Yepanchins, where the prince stays a while and then shortly leaves for the Lebedev house.
Myshkin arrives at Lebedev's looking very happy. Kolya arrives and warns the prince about Ferdyshchenko, who left the house at seven o'clock that morning. As Kolya walks out, Lebedev walks in, complaining that 400 rubles were stolen from his coat the previous night. He thinks the potential suspects are General Ivolgin, Keller, and Ferdyshchenko; he seems to suspect the latter the most. Myshkin tries to divert attention away from the general, suggesting that it was most likely Ferdyshchenko.
Left alone, the prince reads the three letters Nastassya Filippovna wrote to Aglaya. In them, Nastassya Filippovna calls Aglaya perfection, far above herself, and says wants to see Aglaya as Myshkin's bride. That evening, the prince walks to the Yepanchins', but it is so late that most of them are either asleep or about to go to bed.
Myshkin then decides to take a walk to the park, where he encounters Nastassya Filippovna, who has come to see him for the last time. She asks the prince if he is happy, but she runs off before he answers. Rogozhin, who has been with her, tells the prince that they are planning leave the next day. Myshkin tells Rogozhin that the answer to Nastassya Filippovna's question is that he feels very unhappy.
The meeting between Aglaya and Myshkin marks an important event in the development of their relationship. It is the first time they meet each other without anyone else present, and thus the first time they can openly discuss their relationship. Although they come to no definite conclusion, it is the first time they discuss the subject of Nastassya Filippovna, who, from Aglaya's perspective, stands between Aglaya and Myshkin.
In addition to clarifying the relationship between Aglaya and the prince—which nevertheless remains quite confusing for many of the other characters and for us as readers—the meeting in the park also develops the character of Aglaya. She is very much a child, very capricious and quite immature. She is easily overcome with highly idealistic or romantic ideas that seem absurd to any mature or practical adult—even absurd to someone as impractical as the prince. Aglaya's wish to run away from home, for instance, for which she hopes to enlist Myshkin's help, is essentially just an adolescent desire to challenge the authority of her parents and older sisters. Along the same lines, Aglaya boasts having read books that her elders have forbidden her to read. She seems, above all else, to want to establish herself as a free and independent adult in the eyes of her family. Ironically, however, the means by which Aglaya seeks to do this—running away from home and so on—clearly demonstrate her childishness.
Aglaya's fascination with the figure of the "poor knight," which she associates with Myshkin, is another example of her obsession with romantic ideals. She believes that she completely understands the prince's relationship with Nastassya Filippovna through this literary model of the poor knight who sacrifices his life for the ideal of a woman whom he has chosen. This interpretation ultimately proves to be an oversimplification, however.
Chapter 8 develops the motif of light and dark that has surfaced before. Throughout The Idiot, the time Myshkin and Rogozhin spend with Nastassya Filippovna are characterized as dark, while light is typically associated with Aglaya. For instance, the prince says he writes the note to Aglaya like to a light. He also says that he hoped for a dawn after the darkness he suffered with Nastassya Filippovna. Even Aglaya's very name means "light." The contrast between light and dark emphasizes the choice between Nastassya Filippovna and Aglaya that Myshkin faces—in essence, a choice between compassion and romantic love. Whereas knowing Nastassya Filippovna brings the prince constant fear and pain because he is unable to save her from self-destruction, his knowing Aglaya is a hope for happiness. Despite Aglaya's whimsical nature, insults, and lies, she makes Myshkin happy. Upon returning from seeing her, he is always overcome with incredible joy.
Nastassya Filippovna's letters to Aglaya once again demonstrate how the former blames herself for her dishonor. Although she loves Myshkin, Nastassya Filippovna deems herself unworthy of being his wife. She sees Aglaya, however, as pure perfection, and therefore tries to do everything in her power to make Myshkin happy by serving as a matchmaker between him and Aglaya. The letters are very painful to the prince, not only because they represent a connection between the two most important women in his life, but also because they remind him of Nastassya Filippovna's unhappiness and his inability to do anything to save her.