The speaker has just finished reading, and the poem catches the moment right afterward. Instead of closing the books and leaving them behind, the speaker finds that they keep going "in me." Reading hasn't ended; it has moved inside.
The middle lines are the most interesting. "Other matters colors pains" has no punctuation, so the words run together like a small flood of things the books left behind: ideas, images, feelings, even hurts. These belong to other people and other stories, yet the speaker says they "are my own / and near." The word "near" matters here. It suggests closeness, as if the borrowed experiences are not distant or abstract but right beside the speaker, almost within reach.
The mood is quiet and reflective, with a gentle sense of wonder. There's no sadness at finishing, just a calm recognition that reading changes who we are and that we carry what we read.