Friedenthal describes the adventures of Laurentius Hylas, a student travelling from the University of Leiden to the Academia Gustavo-Carolina in Tartu, Livonia.
Laurentius arrives in Estonia and Livonia some years before the end of the 17th century, together with his parrot Clodia. The parrot’s sanguine temperament is supposed to help counteract the melancholia that affects Laurentius. Tartu has a reputation as a city of muses, but Laurentius sees starving people behind the city gates and feels the dampness of the houses. Thus, his melancholia worsens and he starts to suspect seeing again the ghosts which have haunted him from his childhood onwards. Laurentius begins to feel the black bile inside him piling up and slowly descends into a dreamlike disease where he is unable to differentiate reality from unreality.
Everything he eats tastes of mud and putrefaction, and he feels weaker and weaker every day. He tries to find some cure for his disease but only manages to arouse suspicion of witchcraft. He feels that the suspicion is somewhat justified as he believes that he is the bearer of an evil eye, with everybody who looks into his eyes falling ill or having some kind of accident.
Laurentius hears a professor talking about the medicinal theories of Boyle and follows his advice of moderate bloodletting to cure his condition. Unfortunately, the process does not work and Laurentius faints from loss of blood. In the haze of weakness he sees a girl who has, “eyes like gold, like the dark honey, her breathing like humming”. The girl offers him bread and, after that, Laurentius regains some of his strength. She starts appearing at night offering him more food and, later, Laurentius begins to discover that strange events are happening around him. He is unsure if it is possible to explain them naturally or supernaturally, as the competing philosophical theories he follows permit both.