The Lightning Tunnel

Because they say;
"there is light at the end of the tunnel",
Isn't a good reason to enter the tunnel.

The actual fact is;
Not every tunnel yields light.
Some may even result in greater and greater darkness.

So my dear,
Dissect the tunnel,
And see if it can bring you any light.
If not, don't even bother going in.

Choose your tunnel wisely.