File updated. Changes made:

Science hook added: Interoceptive pathways + vagal tone named in the opening two sentences, conversational register.
Teacher-as-confirmation added: Thich Nhat Hanh's interbeing teaching (cloud/rain) placed mid-practice as validation of what the science names — form dissolves, substance remains.
Universal truth woven in: "the story that was never quite accurate" lands near-verbatim at the third-exhale instruction, grounding the arc theme in the body rather than as a concept.
Voice: warm, second person, somatic throughout — no clichés.