When you first move into a dark space from a bright one, you can’t see. Your eyes need time to adjust to the darkness but eventually, they do. In fact, human night vision is incredibly good when it’s allowed to be; most humans can function perfectly well in nothing but starlight if they’re given enough time to adjust to the conditions.
When you first move into a bright space from a dark one, you can’t see – and you’re in agony. The sensory overload causes physical pain. You recoil from it. You squint your eyes, turn away from the light, shield your face. The very thing your eyes need exposure to in order to readjust is also the thing you fight to avoid.
The descent into darkness is gentle. At first you can’t see, but the world gradually fades into view as more and more detail reveals itself to you. The world comes alive, sharing secrets one by one until you’re wrapped in a new world. And that dark world has literally, physically changed you – your eyes are a different shape, different chemicals start firing out of your brain.
The world makes it painful to leave it. It wraps its shadowy arms around you and it changes you in such a way that makes it harder to leave it.
There are other kinds of darkness, and they do the same thing. It wraps you up and makes the light painful. The transition down was gentle and easy. The transition up is painful and hard, so part of you – maybe a big part – resists doing it.
The first glimpse of light can be so blinding and painful that you retreat even further down.
But you have to remember that your eyes adjust. In both directions. The light won’t kill you; in fact, it will save you. You just have to endure the temporary pain of the transition. Your eyes adjust. So does your heart.
The Opportunity Machine 