See

"Of Central Significance" series.
 
Representative of the Eye of the Self looking out of the triangular window into reality. The soul in matter.
The triangle represents the 3 eyes of our physical being that the soul has to perceive with - solar masculine eye of logic, lunar feminine eye of emotion and third eye of insight.
A green spiral takes you to the Heart centre giving physical life, and white for the spiral spiritual Life Force emanating from the Centre, animating and binding all life. Red grounds the experience of life. It is the blood pulsing in the veins of a physical body. And calls your attention to look! Yellow is for the ego identity. Green balance and harmony. The green earth where life plays out.