The speaker compares themselves to an open book, and the comparison is really about being honest and available to others. Anyone can read them or ignore them, and it won't change what's on the page. The book can't run off or fly away, so all it can do is sit and wait, which the speaker presents as patience rather than helplessness.
The tone is calm, almost cheerfully accepting. Phrases like "absorbed by the next sponge" and "public transit for ideas" add a light, slightly playful touch, picturing the book as something ordinary and useful that carries knowledge from one person to another. The speaker doesn't seem bothered by whether readers love, hate, laugh at or shrug off the book. "Makes no difference" suggests a quiet confidence: the speaker knows who they are and doesn't need approval. The poem ends on waiting, which leaves a steady, open, hopeful mood.