All of the planets except the Sun and Moon appear to move backward from time to time. This movement is called retrograde
motion and is an illusion caused by the Earth overtaking another planet's speed or motion. But is there more to this than just the scientific
explanation? Of course there is.
The universe is rich with symbolism and meaning, both hidden and apparent. It is no coincidence that the Sun and Moon which have no retrograde movement rule only one sign each. Nor is it a coincidence that the other planets which have forward AND retrograde movement rule two signs each.
When a planet is moving forward in its natural easterly course through the zodiac it is expressing in its natural or true rulership sign mode, whereas when it is in retrograde or westerly motion it is expressing in it's substitute or night rulership mode.
Mars in forward motion, for example, is expressing in its natural Arian mode whereas Mars in retrograde motion is expressing in its unnatural or substitute Scorpion mode. Below is a list of the planets and their sign expression modes for forward and retrograde motion...