Answer: To explain how she wrote a terrifying novel at such a young age,
Step-by-step explanation: Mary Shelley wrote Frankenstein when she was just 18 years old and it was published when she was 20, in the introduction to this novel she explains that she, Lord Byron and Percy Shelley (her husband) were having a competition to see who could write the best horror story, after a long time thinking about what she could write, she had a dream where she saw a man bringing some kind of monster to life, so she write that story in a few pages and then she developed it until it became a whole novel.