Origin of Vastu Shastra, Vastu Purush Mandala:
Vastu Shastra: According to ancient texts there was a demon named Andakasur who created havoc in all trilokas, to destroy him lord Shiva fought with him for thousands of years. During the fight a sweat drop from lord Shiva body fell down which spread whole universe from which a dangerous demon emerged. By looking it, all gods were afraid and went to the shelter of Lord Brahma. He suggested gods to throw that demon on earth such a way that his face should face towards earth and sit on it so that I cannot be raised again.
Looking at the posture of the demon, Lord Brahma felt he looks like Vastu purush, that demon started crying and pleaded Lord Brahma saying that I didn’t make any sin or harass anyone but still all gods are torturing me by sitting on me. Pleased with him, lord Brahma wished him a boon that from now he will be known with the name Vastu Purush. Also anyone who plans to start new construction of house, palace, temple etc. first they need to perform ritual to you in order to complete it successfully.
Place where lord Eshwar resides is known as Eesanyam(north-east), lord agni – Aagneya(south-east), lord Nirruthi – Nairuthi(west-south), lord Vayu – Vayuvya(north-west) direction. Also lord Indra resided towards East, South – lord Varun, West – lord Yama, North – lord Kubera. If our house construction is made in such a way that gods residing in all 8 direction are satisfied then they will lead happy life with all kinds of wealth, health and prosperity.
There are many strong points that support Vastu Shastra, our ancient knowledge of construction is created in such a way that even modern science agrees many points. Vastu Shastra describes about how a construction need to be done considering all five elements of nature. You might have heard many people saying water need to be stored below in eesanya direction, doors should be placed in particular direction (based on facing of house), etc. If your house is build accordingly then positive energy increases and our thoughts and acts move in positive direction.