Two scenarios that hold some kind of hope are..
- The tunnel is long and the light is presently beyond our visual range..
- There is a curve or gradual change of elevation in the tunnel of which we are blissfully unaware..
Not being able to see a light presents us with other possibilities of a more negative nature..
- Whoever or whatever we seek at the other end has turned the light off..
- We have mistakenly entered a cave..
Endurance, a key factor when negotiating tunnels, can be tempered by many things, the most important being the joy of reaching what we hope will turn out to be a perceptible gain at the other end.
I find myself in a tunnel presently, endurance and faith (yes, we need this too) are not in short supply, and I know that there is a light at the end.