How does Northup use tactics of submission and resistance in response to Tibeats murderous cruelty?

Solomon returns to light and dark to discuss his feelings and his circumstances. After Armsby tells Epps about the letter Solomon wanted him to take, Solomon has to lie to Epps and then privately burn the letter that had been so difficult to write. He says, "The hope of rescue was the only light that cast a ray of comfort on my heart. That was now flickering, faint and low; another breath of disappointment would extinguish it altogether, leaving me to grope in midnight darkness to the end of life" (135). If anything, this passage is even bleaker. We envision a flame, meekly casting light but wavering and threatening to go out. We then see that light being extinguished and a deep darkness falling. This image shows just how tenuous Solomon's clinging to hope is at this point.