Mercury is a highly underrated planet. Why? Because in astrology, this is the planet that rules how we think and communicate, and if we consider it, it is our thoughts that become our ideas and plans, which then become our actions. Everything we think we then we become.

Here is a quick overview of the elements, which are vital when interpreting the planets. Next are motivations. Bear in mind it is only Mercury we are looking at, so the descriptions below only reference how you think and how you communicate your thoughts and ideas. Remember that we utilise Mercury before we activate our other planets. Regardless of the other planetary positions in your chart (the Sun, Moon, Venus, Mars, and so forth), you will always think and speak in the manner of your Mercury sign.

The elements are fire, earth, air, and water, and they describe the basic energy of your Mercury sign. Every sign also has a motivation: Cardinal, Fixed, and Mutable.

Mercury in Fire Signs: Aries, Leo, Sagittarius
Fire signs think fast and speak with little or no prior thought. They often rush to be the first to get their point across and can be accused of insensitivity. Their thought process is so fast that they often interrupt if others are slower, usually because their quick minds have already grasped the point. Fire is an element that quickly takes holds and spreads fast, which is why Aries, Leo, and Sagittarius Mercurys are intuitive, spontaneous, and quickly enthused by an idea. They are also easily roused to aggressive speech when others don't accept their point of view or, at the very least, feel frustration when other people aren't quickly on board with their idea or plan. These signs are the least likely to use silence as a weapon; they're more likely to say what's on their mind.

Mercury in Earth Signs: Taurus, Virgo, Capricorn
Earth signs are cautious with their words and speech and consequently do not rush to give opinions. They react more slowly because they need time to think things through; plus they generally listen to advice and check facts before presenting an idea. This caution also means it takes them a while to adapt to new ideas as they prefer the safety of the tried and tested. Financial gain is often a motivating factor in whether they accept an idea or not; it has to have some grounding and offer tangible and concrete results. These signs are likely to prefer silence to saying something they aren't yet sure of.

Mercury in Air Signs: Gemini, Libra, Aquarius
Air signs use pure logic when making decisions and speaking. They actively avoid using feelings in the decision-making process and weigh the pros and cons of an idea as sensibly and calmly as they can. Making a decision can be their hardest task as they are prone to changing their minds. They are happy to listen to other people's points of view and take their opinions on board, but rarely are they personally interested in the outcome of any decision. The air signs rarely if ever use silence as weapon because it is an emotional response, and they are rational decision makers.

Mercury in Water Signs: Cancer, Scorpio, Pisces
The water signs are emotional in their speech and base their thoughts and words on their feelings. They are rarely logical. And though all are emotional thinkers, these three signs have distinct differences in how they think and communicate. Cancer can become very aggrieved if hurt and will speak up. Pisces, even although they are aware of everything going on, will rarely say anything that will offend another. A Scorpio, on the other hand, is famously uncommunicative, especially involving revealing anything about themselves. It's quite possible they could choose to use silence as a weapon whereas Cancer rarely does and Pisces would never do anything to hurt another person, even if they've been on the receiving end of unkindness themselves.

Motivations
These terms describe whether a sign is a proactive thinker, fixed in their thoughts, or flexible (also called mutable) in their opinions and ideas.

Cardinal signs: Aries, Cancer, Libra, Capricorn
These signs possess leadership qualities and use their initiative, making them often trendsetters or leaders in their field. They can take charge (often preferring it) and inspire others to action. They're resilient thinkers who quickly recover from setbacks because of their positive mindset. When life pushes them down, they soon rise up by taking action to initiate change. Cardinal signs can verbally strike when what they love and care for is threatened in some way.

Fixed signs: Taurus, Leo, Scorpio, Aquarius
These signs find it hard to change the way they think once they have made up their minds. A fixed mindset means that in addition to refusing to alter their behaviour to suit others, they prefer life to remain as it is. Advice or suggestions from others is often ignored; they go their own way. They are more likely to keep quiet in aggressive situations and rarely if ever change their minds once it is made up.

Mutable signs: Gemini, Virgo, Sagittarius, Pisces
These signs are flexible, open to change, and adaptable enough to fit in with others. This applies both in their jobs and personal lives. Mutable signs find it hard to make up their minds because they see all sides of an argument and appreciate that everyone has a valid point. They have no motivation to verbally attack others and prefer to adapt to others' needs, giving in or agreeing when in an argument.

Excerpted from Secrets of Mercury by Andrea Taylor.