The light that enters your eye makes a circle on your retina, an illuminated disc that has a defined border. Do you ever think about that edge? Inside is everything you see, from the sharp center to the fuzzy periphery. It feels like everything, but cross that line and suddenly there's nothing. Not darkness; nothing. Trace a line across the back of your head from one ear to the other—what's back there? Blackness? Void? No, but whatever it is, you are simply unaware of it. Will you poke at those boundaries, try to fix them in your sights? Perhaps from the corner of your eye, track a fingertip as you move it backwards, until finally it passes from view? Things simply become indistinct, without beginning or end.

Just like life.