After reading about Plato, Sophie tries to follow the path that Alberto's dog Hermes had taken into the woods. She comes upon a little lake and sees a red cabin on the other side of it. Without knowing why, Sophie uses the little rowboat at the shore to go over to the cabin. She knocks, and then enters, and inside she sees paintings entitled "Berkeley" and "Bjerkely." By looking around, Sophie figures out that the cabin belongs to Alberto and Hermes. She looks at herself in a mirror and thinks that her image blinks back at her. Then Sophie finds Hilde Møller Knag's wallet inside as well as an envelope with her name on it, which she takes. She runs away when she hears Hermes barking, and she cannot row back across because the boat slid down the bank into the middle of the lake. Sophie reads the questions in the letter, but does not think much about them because she has to explain to her mother what happened without getting her mother too worried. She explains everything away without mentioning Alberto and convinces her mother that she does not have a boyfriend. Her mother tells her the cabin she went to is called the major's cabin. Sophie writes the philosopher a letter, apologizing for her actions, and then thinks about the questions he gave her. Then she talks with her mother, who feels she is growing up very fast and is surprised to learn that Sophie is not excited about her approaching fifteenth birthday.
Later that afternoon, Sophie receives a package containing information on ##Aristotle# plus a small note saying that Alberto is not upset with her but that he will have to move. Aristotle, she learns, was a pupil of Plato's. His project involved studying the changes within nature, and he believed in the use of one's senses. Aristotle believed that Plato's world of ideas did not exist but that the eternal idea was really a concept—the idea of a horse that we have after seeing many of them. Therefore, that eternal idea is in our minds but it comes from the natural world. He did not think there was any reality beyond what we could perceive. Aristotle felt we have innate reason, but not innate ideas. Things have a substance and a form, and the former describes their physical characteristics while the latter describe their limitations or possibilities. Aristotle believed in different types of ##causality# one of which was "final" cause, the purpose that he assigned to everything in nature. For example, it rains "because plants and animals need rainwater in order to grow." He attempted to categorize nature and also founded logic. Aristotle sees man at the top of nature followed by animals and then plants, and God to him is the force that set the stars in motion. He believed monarchy, aristocracy, and democracy were good forms of government but warned against the dangers of each. Unlike Plato, he viewed women as "unfinished men." Aristotle's ideas have a great effect on Sophie, and she organizes her room after reading the letter. Then she has another discussion with her mother, who thinks her daughter is growing stranger and stranger.
In a way, Sophie's life has become a mirror of the philosophy that she studies. Her sensory experiences—the postcards sent to Hilde, the mirror that blinked at her—are in direct conflict with what her reason tells her could be possible. The same conflict between what perception and reason that the ancient Greek philosophers struggled with has become apparent within Sophie's life. Everyone faces this sort of conflict, but for Sophie it has become critical. One's image in a mirror blinking is something that reason tells us is completely impossible—you can see someone else blink, but not yourself. Many of the philosophers that Sophie has read about have attempted to resolve the apparent disjunction between the senses and reason, but in Sophie's case it appears that either one or the other must be wrong. If she really did see herself blink, then either reason cannot be trusted or the senses cannot be trusted.
Aristotle provides a good example of the advantage that we have when studying a philosopher who wrote many years ago. His idea of final cause, for example, modern science would completely disagree with. However, in biology we have taxonomies. The forms of government he discusses have all been tried and it is still unclear which is the best form. It is somewhat incredible that his ideas have survived for over two thousand years. There are different degrees to which a philosopher can be wrong. Aristotle's view of women, for example, was wrong, but changing it does not undermine the whole of his philosophy. So in a way we can rectify what we disagree with without disturbing what we still agree with. We may disagree with Plato's world of ideas, but his concept of ordering society through reason can hold up without that other idea.
Sophie's mother represents a practical foil to all that Sophie learns. Although her mother is not very philosophically inclined, she is a good mother who wants her daughter to be happy. Whenever Sophie tries to introduce her mother to some sort of philosophical idea, her mother begins to worry about Sophie. Sophie's mother illustrates the irony that philosophy is something that everyone should be interested in because the questions it addresses apply to everyone, yet many people are uninterested. Sophie's interactions with her mother can be viewed as a metaphor for conversation between a philosopher and one who is not interested in philosophy, for it involves them talking completely past each other.