From the Dead Sea Scrolls we find the "Sons of Zadok" (Essenes ?)
The Sons of Zadok reveal a dualistic language to describe the options in the universe, being light and darkness.
In their Manual of Discipline:
"God has created man to govern the world, and has appointed for him two spirits in which to walk until the time of his visitation: the spirits of truth and falsehood. Those born of truth spring from a fountain of light, but those born of falsehood spring from a source of darkness. All the children of righteousness are ruled by the Prince of light and walk in the ways of light, but all the children of falsehood are ruled by the Angel of darkness and walk in the ways of darkness."
Contained in man is the "nature" of both light and darkness "appointed by God" as spirit.
The code of both exists in man. We choose which to live by. "Way of Light" or "Way of Darkness"