The passages are not flat; they slope, they have breakdown piles, they have edges.

Navigation without light is not merely difficult.

It is, at any real distance from the entrance, potentially fatal.

The ancient miners understood this.

Their torch management — the bundled cane, the caches of unused torch material found deep in the cave — reflects a systematic approach to the problem of light.

They brought more than they expected to use.

They cached reserves.

They presumably had protocols for what to do if a torch failed: how to get a flame from another bundle, how to extend a dying torch’s useful life, when to turn back if the light reserves were insufficient.