Final answer:
The details in the text suggest that Jack is confronting a supernatural occurrence which conflicts with his rational view of the world, a common theme in gothic literature.
Step-by-step explanation:
The student's question seems to be asking for an interpretation of a literary excerpt in which the character Jack, a sane and healthy man, is confronted with what he believes to be a supernatural apparition. The underlined details in the provided text support the idea that Jack is shocked and struggling with the encounter of the supernatural in an otherwise normal, daylight setting. The details underline his sanity and the stark contrast of the supernatural event to his average life. This occurrence defies logic and Jack's well-educated reason, emphasizing the theme of the supernatural intersecting with the rational world. Such a scenario is typical in gothic literature, where characters often wrestle with their perception of reality when faced with inexplicable phenomena.