Another day turning in circles,

I cut the same doors in my chest,

So you can see me with the top of your fingers,

Hidden in my lungs, I take thin samples,

Place them in Petri dishes and align them,

They are the only proof you breathe like me,

So you get why I schedule for you daily,

This private tour of lights and shadows,

Save puzzle pieces in my cells,

And wait for you to knock on my sternum.