What metaphors are used in A Wild Sheep Chase by Haruki Murakami?

In Chapter Seventeen, the Boss' secretary metaphorically divides the empire into two parts—those of the Gain and the Will. He further explains that the hand-drawn image of the sheep was drawn by the Boss while in the captivity of the U.S. doctors, and that the sheep was in at least eighty percent of his hallucinations. He spent the rest of his life looking through sheep references, trying to find something only he understood, which is how the empire stumbled on the photo used by the main character.