One must walk in darkness before he realizes he needs the Light,
and cries out for it.
The Darkness doesn't teach the Truth.
It is without Life.
God set apart the Darkness so that when Man fell into it by his own choice,
he would realize he needed the Light to live,
enabling him to cry out to God who was waiting for him to repent (turn away from)
of the Darkness back to Him into the Light of Life.