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.

727. And pearls. This symbolizes the concepts of goodness and truth contained in the Word among Roman Catholics.

In the spiritual sense pearls symbolize concepts of both celestial and spiritual goodness and truth that come from the Word, in particular from its literal meaning; and because pearls symbolize those concepts, therefore they are mentioned after purple and scarlet and after gold and precious stones.

These concepts are symbolized by pearls also in the following passages:

...the kingdom of heaven is like a merchant seeking beautiful pearls, who, when he had found one pearl of great price, went and sold all that he had and bought it. (Matthew 13:45-46)

The pearl here symbolizes a concept of the Lord.

The twelve gates (in the wall of the New Jerusalem) were twelve pearls: each individual gate was of one pearl. (Revelation 21:21)

The gates of the New Jerusalem symbolize entrance into the New Church, and the entrance is made possible by concepts of goodness and truth from the Word.

Do not... cast your pearls before swine, lest they trample them under their feet, and... tear you in pieces. (Matthew 7:6)

Swine symbolize people who care only for worldly wealth, and not for spiritual wealth, namely for concepts of goodness and truth from the Word.

Because Babylon symbolizes a religion that has cast out all concepts of goodness and truth from the Word, we are told concerning it:

The merchants of the earth will weep and mourn over (Babylon), because no one buys their merchandise...: merchandise of gold and silver, precious stones, and pearls... (Revelation 18:11-12)