Authority

It was indeed easier to understand.

Although it was understandable, one would still need several minutes to ponder upon the concept and had to be equipped with related knowledge.

A simple example was how boiling a kettle of water required heat energy.

Aside from all those machinery from the old civilization that could provide heat energy, the most primal way would still require some combustible material and a fire. The materials were used to keep the fire burning and the heat energy from the fire would boil the water. It was considered a conversion of energy.

During the process, the heat energy from the fire would spread out into the air, so it would take time to boil the water. The heat from the fire could not reach the water instantly and raise its temperature to 100°C. 

It was not exactly a solid example, but it explained the energy conversion rate problem well.

So, what was Yang Kong trying to express about the Universal Source Rock?