The purpose of the light was to enlighten, to give man a knowledge of God, of His purpose, and how man might fulfill that purpose. The message revealed by the light was revolutionary to the extreme, the very opposite of what the philosophers and religious teachers had held for generations. Blessed are ye, when men shall revile you, and persecute you, and shall say all manner of evil against you falsely, for my sake. So it may seem to a world that is blinded by its own idols. Men make a deliberate choice, but because of the corruption of the heart, the natural choice is darkness and a resistance to the light.
Truth is that which is real.
The light reveals reality about Yahweh and His purpose, about man and his destiny. The darkness is the opposite of reality, including religious ideas invented by men, beliefs upon which they stake their lives, although none of them are true. Everyone that does evil hates the light, and comes not to the light, lest his works should be reproved. He said that life is more than things and that to lose life for His sake is to gain it, that when one makes Yahweh's kingdom and righteousness his first priority, all the essential things will be provided. He revealed that our real wealth is that which cannot be taken away from us again our will, such as faith, hope, and love.