Vastu shastra literally means the knowledge of one's physical environment. It is an architectural science and has been in practice for thousands of years. It originated in India and was first mentioned in the ancient Indian texts called the Vedas. The sages of old developed the principles of vastu through careful and precise calculations. It has been tried and tested in many kinds of constructions and has always turned out to be successful.
According to vastu, there are five basic elements: earth, sky, wind, fire and water. These elements have to balance out while constructing any building. If there is any imbalance in these elements, then there will be an imbalance in every aspect of your life. As with everything else in the universe, the five elements also have energy. So, vastu takes into account the energies of the earth, wind, sky, water and fire. It also places emphasis on solar and lunar energy.
Apart from energies, vastu principles are primarily based on directions. For example, the east is an auspicious direction as the sun rises in the east. Since solar energy is life giving, it is also considered to be lucky for all aspects of life. Wind, water and fire are meant to be in specific directions. If care is not taken with the placement of other elements, then there could be disharmony.
Vastu can have a positive physical, mental and spiritual effect on you. Some of the physical advantages of vastu are: good ventilation, good use of space, use of colours in such a way as to provide a soothing and calm refuge from the world outside, and general physical well being. You tend to sleep better and are more energetic during the day.
The mental or psychological benefits of vastu are the fact that you feel a sense of well being in your home. You can let go of any tensions that you may have and just be relaxed and happy in your space.
The spiritual benefits of vastu are that you become more aware of the cosmos, of the "bigger picture". You become relaxed and tend to generate a healthier and happier outlook on life. Your ability to solve problems becomes sharper and you tend to become more intuitive.
Following vastu principles does mean that you will never suffer from any bad luck. What it does mean is that these principles will help you deal with any kind of circumstance, good or bad, in a calm manner. Vastu believes that we are intimately connected to all the energies around us. So if there is an imbalance in the energies around us, it will affect us as well. Vastu shows us how we can correct those imbalances in our environment and live a happier and healthier life.