Passage Summary: Two authors used the exact same weird metaphor in their books. Since it's so unique, the person who wrote the later book must have read the earlier one.

Conclusion: It is highly probable that Grey read Jordan's book.

Reasoning: Grey and Jordan used the same highly unusual metaphor in books published seven years apart, and it is unlikely they both came up with it independently.

Analysis: The author assumes a direct 'A caused B' relationship, but in the world of literature, things are rarely that simple. To weaken this, we should look for an alternative explanation for how that metaphor ended up in both books without Grey ever cracking open Jordan's work. Perhaps they both stole it from a third, even older book, or maybe they were part of the same eccentric writing circle. Look for an answer that provides a common source or an intermediary that breaks the direct link between the two authors.