A person spends an hour picking raspberries and comes away with purple juice on their palm and fingers. The poem follows what happens next: the stain seems to fade by afternoon, as if the skin has absorbed it. But new marks show up, brighter and stranger, on the back of the hand and up the arm. The speaker notices these slow changes with quiet curiosity rather than alarm.
The title, "Invisible Ink," hints at the idea that the body keeps a record of what it has done, even when the record seems to disappear. The last image is the most striking: the skin becomes "parchment," and the marks look like the traces of "dry nibs" trying their points, as if a pen were testing itself before writing. The mood is calm, observant and a little playful. Ordinary outdoor work turns into something like writing, with the body as the page and the raspberry patch as the author.