The speaker takes the idea of digestion literally and applies it to reading. Instead of just reading a book, they break it down the way the body breaks down food, hoping to understand it more clearly. The poem then shows what that process yields: from each letter comes light, and from each word comes spirit. The book is broken into smaller and smaller pieces, and at that level it starts to feel almost sacred.
The last lines turn toward something more personal. What the speaker wants from this slow, close reading is "being other and not / me at all." That suggests reading as a way of stepping outside the self, letting someone else's words take over for a while. The mood is quiet, calm, and a little hungry. There's real appetite here, but it's patient and reverent, not greedy. The short lines and plain wording make the poem feel like a small private act, much like the reading it describes.