Pi in the Sky
One phase in the planning of the creation of Planetary Essences is finding the right time to make each of the essences: a time when the planet is particularly powerful or influential. The obvious time for the making of the Mercury Planetary Essence is when the planet is moving at it's quickest through the zodiac. Of all the planetary motions Mercury's is the most extreme as it speeds up and then slows down to stationary, speeds up again in the opposite direction (referred to as retrograde motion) slows down to stationary and once more speeds up in direct motion. From an astrological perspective this causes it's strength to wax and wane.
If you want to know more about the planetary motion of the planets trough the zodiac and why Mercury's varies so much follow this link. http://www.nakedeyeplanets.com/movements.htm It is definitely worth a look because even though a lot of technical data is presented there are some rather clever graphics that give a purely visual explanation..
I was brought up playing a wide variety of musical instruments. At school I was either found on the rugby pitch or in the music department. My involvement with music stopped however when I became seriously involved with astrology. I would go to parties and gigs, see others playing music and think, "I use to do that," but not miss it at all. That part of my brain used for music was the same part used for astrology. I guess that is why it is referred to as the music or harmony of the spheres. And when you study the planetary motions in depth it is like reading a symphonic music score, but much better. And there is something truly magical about Mercury's direct and retrograde motion through the zodiac. Mercury changes direction 2xPi a year. This means Mercury goes direct Pi x a year and Mercury goes retrograde Pi x a year.
When I was a kid I remember my maths teacher bringing a book into class: it contained nothing but pages and pages of numbers. It was Pi expressed to thousands of decimal places. Now Pi has been calculated by a computor to 5 trillion decimal places. 5,000,000,000,000. I bet that took some time. This number, which we all used as kids to work out the circumference of a circle, does truly come from infinity.
Expressed as a fraction Pi is much simpler: 22/7 (22 over 7) or 3 and one seventh. As far as Mercury's change of direction through the zodiac is concerned, it means that over a period of 7 years Mercury goes retrograde (or direct) 22 times. This 7 year cycle is not exact, there is a discrepancy of 5 days. However, 22/7 is not a perfect expression of Pi: it is inaccurate by 0.04%. A more accurate expression on Pi is 355/133. Therefore for Mercury this means that over 133 years the planet, as viewed from Earth, goes retrograde 355 times. Again the cycle is not exact because there is a discrepancy of 2 days, but over 133 years that is very small and reflects the fact that this fraction too has an inaccuracy of 0.00000849%.
One last Pi fraction 104348/33215: this is accurate to 0.00000001056%. A palaeontologist can tell you some very general, sketchy facts about what was going on thirty three thousand two hundred and fifteen years ago However, pi in the sky can tell you to within one day the position of Mercury in the zodiac on any day of that same year.