Try this experiment: Close your eyes tightly, walk around your room towards the door. Obviously check before you start that there are no children, animals, toys, books, etc. underfoot.
Did you manage it?
Even if you did not actually do it you felt that you could as most people can do this in their own surroundings. We know our own home well-our own world; where the furniture is placed, the location of the doorway, that awkward step. Things familiar to our touch that help us navigate in the darkness.
It's a very different matter when we are in an unfamiliar home. In this situation we fumble around and bump into things until we learn to be more cautious, to move more slowly, to reach out into the darkness. Our mind-map that we use for our familiar surroundings is now of no use to us. We need a new map.
In Jesus' day small oil lamps were the only source of light and darkness was a normal condition. Darkness meant danger, it restricted occupations, it curtailed travel, it required detailed mind-maps. For everyday living in such a situation we would feel to be in unknown territory, to be in a foreign land, to feel 'lost'.
As in the physical, so it is in the spiritual.
Jesus uses the terms darkness and light throughout Thomas. Jesus knows of our spiritual darkness. And he knows that we while we may consider ourselves to be spiritual, we may be still walking around in our own familiar surroundings, amongst our old furniture, our old baggage, with our old mind-map.
Jesus wants us to move from this darkness to the light. We have however, to move from our familiar surroundings where we can walk blindfolded along our well-known pathways. Courage is needed to enter the darkness of this new territory, to embrace the unknown. We do it with Jesus' promise to provide sufficient light even it's the smallest glimmer, to help us create maps for this new world.
His disciples said:
Show us the place where you are,
because it is necessary for us to seek after it.
He said to them:
He who has ears let him hear;
There is light
at the centre of a man of light,
and he illumines the whole world.
If he does not shine,
there is darkness. [#24]