Final answer:
Twain continues the lightened mood of chapter 20 in the last few lines of Huckleberry Finn by celebrating the beauty of the natural world coming to life at the beginning of a new day. The description of the sunrise, the nice breeze, and the song-birds all contribute to creating a lightened mood.
Step-by-step explanation:
Twain continues the lightened mood of chapter 20 in the last few lines by celebrating the beauty of the natural world coming to life at the beginning of a new day. The description of the sunrise, the nice breeze, and the song-birds welcoming the new day all contribute to creating a lightened mood. Additionally, the narrator's own reaction of feeling meaner than the meanest man in human history adds a touch of humor to the passage.