To build something generally means to put together a variety of simpler pieces to make a useful and more complex structure, as to build a house out of wood or bricks, and it is commonly used this way in the Word. In the land of Shinar men wished to build a tower, and in the new testament Jesus advised that a wise man should build his house on a rock. But in a representative sense the meaning is to build a mental and spiritual structure, like the doctrine of a church or the individual concepts of spiritual reality in a single mind. The building materials are representative also. The tower of Babel was built of brick, which is man-made rock, or representatively, man-made "truths", that is"truths" not from God but ideas of spiritual reality thought out by men. The house that the wise man would build was founded on a natural or "God-made" rock, which means a truth from the Word.

'Mansions,' as in Genesis 6:14, signify the two parts of a person which are the will and understanding. 'Mansions,' as in lowest, secondary, and third, represent scientific, rational, and intellectual ideas.

(References: Arcana Coelestia 638)