What does this passage refer to? [S]o he growled from his depths, hackles rising out their outrage. "Bear up, old heart! You've borne worse, far worse,

If sounds as if it refers to his aching agony within his situation. ¨Bear up, old heart! You've borne worse, far worse,¨ shows how everything is affecting him. This is his attempt to tell himself to stay strong in time of dispair.