In just a few lines, this small poem pictures someone preaching, but not in a soft or comforting voice. The tone is "hard as an old pair of tweezers," an image that feels oddly specific and a little surprising. Tweezers are thin, precise, and slightly unyielding. They pinch and pick out small things, which suggests a voice that is narrow and insistent, one that tries to pull a single memory out from the clutter. The word "old" adds wear and stubbornness, as if this way of speaking has been used many times.
The last two lines turn the poem toward its purpose: the preaching is "against forgetting." The line break splits "for-/getting" in two, so the word seems to catch and falter, almost forgetting itself. The speaker seems to feel that remembering matters, and that it takes a stern effort. The mood is austere and determined, but also quietly weary, like a duty carried on without much hope of applause.