Lightning is one of the many elemental essences of life. It comes from the sky and blesses the earth with nutrients. Lightning also exists in our neural pathways as slight shocks that enable man's movement.
The first page of the manual explains the essence, importance of lightning and how it was distributed in the world, but what really peaked Wilder's intrigue on the first page was the definition of lightning when it came to the world at large.
Apparently, even at the Earth's core, lightning in the form of shocks existed, just like in the neural pathways of the human body, and it performed almost the same functions.
This explanation was a bit far-fetched, but it was also quite interesting; it was insinuating that the movement of the Earth was a result of these slight shocks.