Comment by adgjlsfhk1

> Wait hang on, would they "control" file by finding natural sources (volcano, lightning strike wildfire, etc.) and then make use of that source for controlled sources of light/heat/etc?

Pretty much. Being able to transfer/build a fire is a lot easier than starting one. Fire starting requires bow/flint&steel and a lot of patience. Control basically means using simple torches to transfer fire from one place to another (where the initial source is either lightning/wildfire or embers of a previous fire).