The Sun is the soul, the moon is the spirit, to them we add mind. Mercury is mind. They are a trinity, for mind is the medium between the soul and the spirit. Mercury the divine being, who is also known as Hermes, is said in the old myths of the ancient occidental wisdom traditions to represent the god of language, science, and philosophy. Let us pull the curtain back then and say that mercury is thought and thinking. Language communicates thinking, thinking has produced the world we live in and made it what it is. Thinking is also though a trickster, it pulls one out of soul and spirit, and while it can lead one to wisdom, it also more commonly leads one to confusion. So mercury is the philosophical trickster.
Let us say then, where Mercury is in your chart is an area where your thoughts will wander. You can have a whole life, with many activities and things to think about, but where Mercury is, that is where your thoughts will naturally go back to. The thinking of that place will be influenced by the sign Mercury is in. They way we think about the world colors how we percieve it, thinking is sense organ. In the prajna paramita when Shariputra is negating sense perceptions as being existent, he says ‘ No eyes, no ears, no nose, no tongue, no body, no mind;’ We have this wonderful faculty then called thinking, which attempts to create and order our perceptions of the world. This is Mercury, uniting the energy of the planets and being a messenger between them as it travels the celestial sphere within and without our being.
How Mercury is aspected will effect your experience of how you think and how you communicate. Mercury aspecting the benefics creates hope while aspecting the malefics it creates fear. If it is retrograde in the natal chart it creates alternate ways of thinking, and alternate approaches to thinking from mainstream thought. (This is where the breakthroughs of novel thought come from, by the way. ) When it is combust it creates thinking that is from the other-side, the upside down, the spirit world. This is because it is not seen by the world, rather it is hidden behind the rays of the solar deity.
Mercury goes retrograde a lot. Three times a year three weeks a time. That is 9 weeks a year. Really though the retrograde cycle is 27 weeks a year for the following reasons. Before it goes retrograde it enters the shadow period, this is a forecast of what will be reviewed when it is retrograde. Here it is traversing the degrees before it is retrograde. During this time, observe the themes that are coming up as a way of preparation for the retrograde. During the retrograde one is rethinking approaches to life, after the retrograde it covers the degrees in the chart for a third time, this is the summation or conclusion of the matter of the retrograde period. It is a wonderful tool for looking at your life and relationships, and making them more appropriate for the narrative you are tasked with carrying out.
The retrograde motion is thus a journey within for review, occurring half of the year, with the direct cycle being a journey without occurring half the year. I feel like if we lived in a less materialistic society judging people by their outer appearance, actions, and possessions, Mercury Retrograde would not be as big of a deal as it is in modern astrology.
Mercury then can be a trickster, because it is reversing itself all of the time. Mercury holds the energy between the Sun and the Moon, between Strength and Beauty. I remember being fascinated by the chaos magic exercises in Liber Null in the early 90’s where one would intentionally whip ones mind into a frenzy of oppositional thinking. This is what Mercury is the wisdom of, holding the space between two different thoughts, thus it is mutable. Mercurial people, that is those who have a strong Mercury in their chart by rulership and thus by extension through being a significant almuten are mercurial. Their lives will always be changing. They are shape shifters. This constant transformation makes them seem unreliable to those who expect solid definitions, but it is not out of malice, a mercurial person is constantly changing, it is their nature.
To master the energy of Mercury in your chart, you will need to do two things that are not easy. The first is to develop a capacity for logical thought that builds on itself and constructs paradigms of truth from the philosophical understanding the unification of experience. Simultaneously you will have to divorce your self from thinking of your thoughts as real or true. Mercury has to become your tool for developing mastery over your sense of self, not a fragmenting fiction of your sense of self.
How to do this is indicated by the location and the condition of Mercury in your chart. For example, if it is in Sagittarius in the fifth house, then it will be through the philosophy of pleasure and enjoyment, such as eastern yoga. Remember though, mercury is the reconciliation of opposites, so it will be simultaneously harmonizing the philosophical path of pleasure and aversion to that path. This does not mean that one has to go have wild sensual experiences, all though one may well do that, it means that one has to develop a philosophy of understanding of that house and sign that is whole. This then will help you to have a sane mind, and there are not too many of those in this world.
Remember, Mercury is where you will reconcile opposite impulses of your soul and spirit. This is true by your natal chart, and where it is transiting the sky right now.