To begin with, let's set the record stright: Mercury is not the only planet to go retrograde. We hear about it a lot because it happens 3 times a year, but actually every planet and asteroid except for the Sun and Moon go retrograde at one time or the other. It is actually rare for there to be a time when we aren't experiencing some retrograde or the other. Every planet from Mercury which is closest to the Sun all the way out to Pluto and Ceres at the outer edge of our solar system goes retrograde. And so do all the Astroids, like Chiron, Vesta, Sedna, Pallas and Juno.
We can better understand retrograde Mercury by taking a favorite comic book character as an example - let's say Zorro with a capital Z. When the planets change directions (and they all do) they make a kind of "moonwalk" in the sky as they appear to zig backwards in their orbit.
These Mercury Retrogrades (and Mars, Venus, Pluto, Chiron or Jupiter Retrogrades). Are zig-zags that the planets make in the sky and they take various amounts of time. A retrograde of Mercury takes 3 weeks, but larger planets like Pluto or Saturn spend up to 6 months or longer in retrograde motion. But just looking at retrograde is to overlook some of the most important elements of the retrograde cycle. That's a lot like eating the frosting and ignoring the cake. Since we want to have our cake and eat it too - we need to understand the whole picture. The picture that retrograde makes starts weeks or months before the retrograde begins, and ends the same amount of time AFTER the retrograde ends. It is a three part process.
The three distinct parts of a mercury retrograde, or other planetary retrograde cycle each have a different character and meaning. Taking one without the others means missing some of the most important pieces of the puzzle. These three phases are 1) the pre-retrograde phase - called Entering the Shadow 2) the Retrograde Phase and 3) the post-retrograde phase - called Exiting the Shadow. Part one is like when Zorro draws the first part of his signature Z. It begins when the planet hits the degree it will return to at the very end of Retrograde. During the Retrograde time the planet appears to move backwards - all the way to the same degree where it began. This resembles the second / slash that Zorro draws with his blade when making his signature as it returns to the same level that the Z began at. Finally the planet changes directions again and makes it's final pass across the same degrees that it has crossed twice already - first when entering the shadow, then in retrograde, and now finally as it is exiting the shadow. And this resembles Zorro's final sword stroke as he finishes off the last flourish of the Z and moves on to new things.
To illustrate what happens during a Mercury Retrograde cycle, just imagine that our Hero Zorro is out and about, doing what he does when he spies a problem. He quickly get's into his "superhero" outfit. We can think of this preparation time as entering the Shadow. Then he runs off and fights the bad guys. We can think of this time as Retrograde, because he has come back to a situation in order to fix it. Finally he turns the bad guys over to the authorities and gets back into his street clothes; which we can compare to the phase of leaving the shadow. Job well done! And he moves on to other things.
By understanding this deceptively simple concept we can see how to make use of any mercury retrograde, or retrograde of Saturn, Mars, Venus, Pluto and even the Astroids. At least we begin to understand how to use the "foreshadowing" period to gain insight as to what we will be reviewing and making changes to during the actual retrograde. This allows us to prepare for what may be coming. Each planet has it's own domain however and they all mean different things. To learn how to make use of the current Mercury Retrograde (or other retrograde planet) cycle visit: http://www.astrologychick.com/RxMercury.shtml