a yellow square, indicating this line as the constituting ruler of the hexagram Six at the top means:

Not light but darkness.
First he climbed up to heaven,
Then plunged into the depths of the earth.


Here the climax of the darkening is reached. The dark power at first held so high a place that it could wound all who were on the side of good and of the light. But in the end it perishes of its own darkness, for evil must itself fall at the very moment when it has wholly overcome the good, and thus consumed the energy to which it owed its duration.