Mercury is also equally important in forming the foundation of your personality as Sun and Moon sign are. The way you process information and express your thoughts are areas that belong to Mercury. Mercury is the closest to the Sun so naturally its impact is quite personal as it is one of the inner planets. Sun is how you project yourself but Mercury is what guides your mental process. It works like a director behind the scenes. If Mars governs your action, Mercury governs the thought process behind it. The sign where Mercury is placed reveals a lot about your thinking pattern. This is the reason why your opinions are different from others. Quite often, your Sun Sign and Mercury Sign are the same as it is close to the Sun.
Have you ever met someone who just seems to think like you and really gets along? Or you might also have met someone who just always shares a different opinion. This is governed by your Mercury sign. People with different Mercury sign have different perspectives and opinions. Mercury in Taurus would have a practical thinking and approach while Mercury in Pisces would be an idealist, someone who thinks creatively than logically. A Mercury in Pisces would always see situations through rose-colored glasses and for them, glass is always half full but someone with Mercury in Scorpio is a pessimist at heart. Someone with Mercury in Aquarius would always have innovative ideas up their sleeves.
Mercury works well in air signs like Aquarius, Gemini and Libra. These signs are practical and intellectual. When Mercury is in a fire sign, native is often an impulsive decision maker. When Mercury is in water sign, native would base his or her opinions on emotions than logic. In earth signs, Mercury makes you an overly cautious thinker but a reliable one of course.
Now different people process the same information differently, which also comes under the realm of Mercury. Suppose you need to solve a riddle. Now someone with Mercury in Virgo would pay attention to every little detail and then come up with an answer. Mercury in Aries on the other hand would trust their first instinct and impulsively give an answer. Someone with Mercury in Cancer would first try to understand how they feel about it. And with Mercury in Aquarius, you might challenge the very concept of the riddle. So, we don’t actually hear two different things, but process the same thing differently, all because of Mercury.
How you articulate your thoughts is also ruled by Mercury. Everyone’s verbal expression differs. People with Mercury in Leo have a commanding way of speaking, as if they are king and you are supposed to listen and bow. People with Mercury in Libra on the other hand are very receptive and know how to put across their point without hurting anyone. When someone with Mercury in Taurus forms an opinion about something, it is solid and difficult to change. People with Mercury in Gemini on the other hand are quite adaptive with their ideas.
Whether your Sun and Mercury fall in the same sign or not also affects how you process information. For example, if your Mercury is in Taurus but Sun is in Aries, you might feel a conflict in forming opinions. The Aries-Sun wants you to react quickly based on instinct while the Taurus-Mercury wants you to raise questions and be skeptical of the ideas. At times however, the combination also strikes a perfect balance like if Sun is in Virgo and Mercury is in Libra. When Mercury goes retrograde, you would need more time and efforts in thinking, making decisions and expressing yourself.