He who is afraid of the leaves must not go into the forest.

Well a forest is filled with leaves (the leaves on the trees) so you shouldn't go in but why would someone be scared of leaves!?

If he is afraid of leaves, he shouldn't go into the forest because leaves fall from trees to the ground, which would make it impossible for him to walk through the forest.

The answer is the narration suggests Usher’s confusion in the wake of his loss. This is the answer because he is walking quickly in uneven paces from chamber to chamber and his skin is pallor which shows us that he is pacing because of a loss. Hope this helped!