There are not many instances that we today have an application for such a question.
Tunnels are few and far in between in our day-to-day travels unless you live where subways or mountain tunnels are the norm.
I can remember as a boy walking through an abandoned railroad tunnel and becoming so very aware at how dark the tunnel is once you leave the light of the opening. With each step I found my trip even more tenuous stumbling over fallen bricks and rocks. Even as I lay flat on my stomach with my face in the dirt, I remember trying to look forward to see if there was light at the end of the tunnel.
That darkness only becomes deeper the further you walk away from the light but if you walk far enough down the tunnel assuming that it is not a dead end you will eventually once again come to the light and find an opportunity to leave the darkness behind.
It’s a safe bet that every human being on earth has metaphorically endured this same experience in some part of their life. Whether by their own choices or by the actions of another, one feels like you are walking down that darkened path that seems to lead only to darker shadows.
You stumble, you fall, you get up and you try harder to make your way through the darkness only to repeat the process again when you once again can’t find the way out on your own. Then eventually in the distance the Light shines through and you race towards it hopeful that you will never find yourself in such a place again.
Once in the Light though, it is easy to forget the darkness and the trials endured and once again stumble away from the Light into the place you never wanted to be again. What is amazing though is the Light is always there to shine on a path to give us the opportunity to come through the trial.
Once through, if we rely totally on the Light, maybe we will never need to seek the light at the end of tunnel again.