According to Brihat Samhita, Vastu was given to the sages from Brahma the ultimate creator. There is a mythology concerning the birth of Vastu Purusha.

There was a Demon, who terrorised the whole earth and heavens and he became the source of trouble to the world. The Gods became infuriated by his acts of brutality and they buried him in the earth by his head embedded in the inverted position, and also started guarding that place.

It became the recognised place of Gods and the buried demon was called Vastu Purusha by the Creator Brahma who also proclaimed that the construction on the earth will only be successful when the Vastu Purusha will be worshipped and respected. This worship and respect meant more than rituals.

.Going by the same anology, Vastu Purusha has been imagined as a man lying with his back upside and bent and his head pointing North and East respectively, whereas his elbows are also bent and point towards North-West and South East direction respectively. His knees are touching the elbows and are pointing the directions of the elbows only.  His feet   and   soles    are joined and are pointing jointly towards South-West direction. In this scheme the naval part of the demon will coincide the centre point of the land and was called Brahma Sthan.

So this symbolic story easily explains the direction allotted to the land and their utility represented by the body parts of the demon, where the most important ones are the head (north-east) and Naval the mid point of the land.  The Vastu Purush is located in such a way that it occupies each part of the lank, however smaller the parts are. The scheme of the land division into 100 right angled quadrangular parts or 81 parts or 64 parts is such that Vastu Purush exists in each and every part which is called Pada also. So in this way Vastu Purusha rules each Pada or Units.   The Chief Technical planner of the earth after Vastu Purusha is Vishwakarma, whose origin and contribution is explained thus- Vishwakarma the Chief Architect was appointed by the Creator Brahma for the help of Prithu, the first emperor of the earth according to one's ehims and fancies but only after the wise advise of Vishwakarma. So Vishwakarma was given the rights to enforce the rules and regulations of the Vastu and he himself could envisage the technical part of the construction without any fear of the royal authority. Vishwakarma was given the responsibility to manifest the divinity of the gods into all the Padas of the land according to the Great plan of the Creator Brahma.