The word 'unfathomable' means not able to be understood.
to 'fathom' is to think or ponder on something so as to understand it.
Answer:
"Under the astonished, wide-eyed moon, with the fires casting strange shadows upon these towering figures, I am rather inclined to believe him."
Explanation:
The use of the words "astonished" and "wide-eyed" that are used to describe the non-human presence of the moon creates a feeling of wonder. It depicts a scene in which the moon is large (wide-eyed) and beautiful (astonished). This and the description of the fires and their shadows creates an almost magical scenario to help the reader envision what the narrator is seeing. The personification aids in this, allowing us to understand how the narrator <em>feels</em> as well (wonder).
The words "casting upon" can also be considered personification, but it is not relevant in this case.
