The square aspect in astrology is where two planets are 90 degrees apart from each other. This is the circle divided by four. The harmony of the three is now disturbed and there is an inbalance that needs to be completed.
Number Four Symbolism
The number four is also the number of the elements; fire, air, earth and water. The symbol for the earth is a circle with a cross through it highlighting these four elements. The number four implies manifestation of something in the earth. With this aspect, there is a desire and an urgency to reconcile tension and achieve something tangible.
We have words in our language implying the tension around the square aspect; 'They Squared up to each other', 'They were Square on'. Since there is a disharmony there is also an energy around the square, something is not finished or is out of balance. It is as if you are a conductor of an orchestra and there is a note out of tune which demands your attention and input to be resolved.
Square Aspect in Astrology
In astrology, when two planets are square to each other in the sky, so they are also in tension in the psyche of the person born under this combination. This is an area in their life that they need to work on and try and find harmony in. There is often conflict around the energies expressed by these two planets. Things do not run smoothly in these areas and there are always issues that need dealing with. Externally these may manifest as tensions and disharmony with people and events, yet they are just an expression of the underlying tension in the person.
Moon & Mercury in Square
If we take an example of the Moon being square to Mercury. Astrology states that the two forces exemplified by these planets will also exist inside the individual but as it's a square aspect, they will be in tension with each other. The force of emotions and neediness and comfort, the Moon, will be at odds with the ability to communicate and express knowledge, Mercury. This person may not be able to easily express his emotional needs.
The tension of the square is further emphasised by the fact that when planets are three signs apart, they are sitting in signs of completely different elements. For example, one planet could be in a fire sign and one in a water sign. Naturally these two elements do not mix, yet the two planets are some how connected and need to be reconciled.
Square aspects are what drive people forward. Somehow they need to be resolved or at least accepted. People with many squares in their natal chart, have an underlying tension and drive. They may not always be comfortable to be around because of the underlying conflicts in their psyches but they are often great agents for change. In their efforts to change themselves and find harmony they often ending up changing the world around them.
Many of the people who achieve most in life are challenged with these squares but they inspire them to great heights. Like inner demons, the person cannot rest until they are dealt with. Ideally a natal chart is a balance of square and trine aspects. The abilities of the trines can be used in an effort to achieve harmony with the squares.