Light which will not turn off

You can start telling the story how the Persians adored fire. “Nowadays, nearby the city of Baku, the churchmen keep in looking after the saint light which will never turn off. They can´t give nothing from this light to anybody. But I managed to get at least some small piece of this light. And here it is.” And now, you can show the light to the audience. The basis of this light is sulphur and wax. This consistence of light is not easy to turn off.