Sternum

In the centre of your ribcage sits a flat bone — barely twenty centimeters long, scarcely a finger's width. You normally do not notice it. Until it makes itself known. A dull pressure behind the sternum, a stabbing burn, a feeling as though a stone were resting on your centre. Sometimes so intense that you think of your heart. Often it is not the heart. Often it is the plate in front of it — the sternum, standing like a shield before everything in you that is most vulnerable.

Anatomically, the sternum is a protective bone. It protects the heart, the great vessels, the central airways. It holds the ribs together, connects the two collarbones, gives the ribcage its shape. It is the centre. The front axis. The point you touch when you say: "I."