Four short lines, and each one works like a nudge. The speaker is urging a group to stand up and act, and the tone is urgent but not angry. It sounds more like someone saying out loud what everyone is already thinking.
The second line pushes back against a fear of being worn out or past it: "we are not rusted." The people addressed still have their strength. The third line, "we need no one but one another," says that help won't come from outside. Whatever change is needed will come from the group itself, and there's warmth in that, a sense of solidarity.
The last line is the surprising one. Matches are fragile and slight, yet they exist to start fires. Saying "match-thin like the truth" suggests that truth may look small and easy to snap, but it can still set things alight. The title, "Instigation," fits that idea. The mood is tense, hopeful, and ready to spark.