Pleurisy

It stings. Not dull, not diffuse — sharp and direct, with every breath. The pleura, that thin membrane that envelops your lungs like a second skin, has become inflamed. Medically it is called pleuritis. The pleura — normally a smooth, painless boundary layer between lung and rib cage — is rubbing itself raw. And suddenly something hurts that you normally never feel: the act of breathing itself.

That is remarkable. You are not feeling the lung. You are feeling the casing. The boundary. The space between inside and outside. And that is precisely where the deeper story begins.