Mood oscillates significantly throughout For Whom the Bell Tolls, but is buoyed by Jordan's feeling that he is fighting for a righteous cause. There exists a mood of contentment that slowly surfaces the closer Jordan comes to approaching self-acceptance and inner harmony.
Toward the end of the novel especially, this mood emerges, dominating the narrative even in the face of Jordan's death. He is satisfied with his life, finding resolution and peace in spite of the pain. His is a conclusive ending, despite his death hanging like a question mark in the air.
Jordan's feelings of self-loathing initially surface towards the end of his life, briefly imparting a mood of despair and distress. His uncertainty fuels his final thoughts in Chapter 43:
You're not good at this, Jordan, he said. Not so good at this. And who is so good at this? I don't know and I don't really care right now. But you are not. That's right. You're not at all. Oh not at all, at all. I think it would be all right to do it now? Don't you?
However, once Jordan is at peace with himself, he feels grounded, settled, content—connected to the nature around him and to his own greater purpose in life.
He was waiting until the officer reached the sunlit place where the first trees of the pine forest joined the green slope of the meadow. He could feel his heart beating against the pine needle floor of the forest.
Compare the above passage from Chapter 43 to the first one cited. In this passage, Jordan's thoughts are calm, rather than frantic. The mood is content, rather than unsettled or despairing.