What does an open flame mean?

Open flame refers to the fire lit by the convex lens reflecting the sun during ancient sacrifice or divination.

Explanation:

1. In ancient divination and sacrifice, bronze mirrors were used to reflect the fire lit by concentrated sunlight.

2. Bright fire.

This is called public robbery.

4. In ancient times, when offering sacrifices or divination, the convex lens was used to reflect sunlight and ignite the fire.

Extended data:

In the case of fire, any burning substance has a process of changing from an unburned state to a burning state. This process must have three conditions, combustible, combustion improver and ignition source, and these three conditions must interact.

Any energy (usually called heat energy) that makes combustible substances react with combustion-supporting substances is called ignition source. According to the different energy sources, ignition sources can be divided into: naked flame, high-heat objects, chemical heat, electric heat energy, mechanical heat energy, biological energy, light energy and nuclear energy.