Monday morning on her way to school, Sophie finds another postcard addressed to Hilde. It is from Hilde's father, who wishes her happy birthday again, although he is not sure if it is still her birthday or the morning after. He says he is sure she knows now why the postcards must be sent through Sophie and also promises to reimburse her for the loss of her wallet. It is postmarked Friday June 15, which is also Sophie's birthday and over a month away. Sophie runs back home and finds that the other postcard was also postmarked June 15. She cannot understand what is going on but only knows that something is very wrong. Sophie runs to meet Joanna, who impatiently awaits her. At school there is a test in Religious Knowledge, and Sophie answers all of the questions extremely well using her philosophy knowledge. However, she does not refer to any of the homework assignments in the class, since she had not done them. The teacher tells her she must do her homework in the future but is satisfied with her test.
After school, Sophie gets a package from Alberto on Hellenism, a period of several hundred years after Aristotle when Greek culture spread throughout many areas. As borders broke down between societies, religious beliefs mixed together. Also, people began to feel a sense of decline in the world. Philosophy became concerned with the way in which people can live a good life, and became intertwined with religion. Alberto describes the Cynics, who believed that happiness had nothing to do with material goods. The Stoics, who came after the Cynics, believed that there was a universal natural law that "governed all mankind." They felt that we are all part of the same nature. The Epicureans were less interested in political affairs and felt that pleasure should be sought in life. But any particular act must be considered in terms of the pleasure it will bring compared to what else it will do. Plotinus, most famous of the Neoplatonists, believed that the world is characterized by opposite poles. One pole is light, called the One, or God. The other pole is darkness, but it is defined solely by an absence of light. Some of the light is inside of the human soul, and so we are all a part of the One. Sophie learns about mystics, who believe in personal experiences in which they lose themselves within a supreme being. Sophie has a mystical experience after reading the letter, and she feels she is a part of a greater cosmos.
On Wednesday, the day before May 17th, a national holiday in Norway, Joanna convinces Sophie they should go camping. Sophie convinces her friend to go to the major's cabin, and inside it they find postcards. All of them are postmarked from Lebanon and addressed to Hilde, care of Alberto. They are all from her father, and the last one tells Hilde to be prepared to meet Sophie, who will probably begin to figure things out. It also mentions Joanna. It is postmarked May 16th. The two girls are very scared, and Sophie takes the mirror back with her. The next morning she finds a new package.
Gaarder suggests that although we learn many things in school, the use of our common sense is not necessarily one of them. Sophie has not done her homework for her Religious Knowledge test, but she managed to answer each of the questions very well using her reason. The philosophy course has taught her that she can think a question through and come up with a good answer to with nothing more than common sense. Furthermore, there is nothing more important to us than the ability to use that reason. Unlike factual knowledge, our reason can be applied to anything. The implication seems to be that learning how to think is much more critical to success than learning any specific set of facts. Sophie is told to do her homework in the future, an important injunction; reason informed by facts will do better than reason alone. For example, it would be very difficult to simply reason out the chemical structure of a compound. On the other hand, knowing the chemical structures for a certain set of compounds is not useful unless they are used reasonably. Sophie feels that she is learning a whole lot more with Alberto than in school, and she may be right, but it is not only how to use reason that Alberto teaches her. Alberto uses factual, historical examples to give Sophie a knowledge base and then she must reason out the philosophies on her own. To memorize what Plato said means little compared to actually thinking about his ideas and coming to an understanding of them.