217. (1) The truths of the sense of the letter of the Word are meant by the precious stones of which the foundations of the New Jerusalem consisted (Rev. 21:17-21). It has been mentioned above (n. 209) that precious stones exist in the spiritual world, as well as in the natural world, and that their spiritual origin is the truths of the sense of the letter of the Word. This seems incredible and yet it is true. And this is why precious stones are so frequently mentioned in the Word; and why in the spiritual sense they mean truths. From this it follows that the "precious stones" of which the foundations of the wall around the city New Jerusalem are said to have been built signify the truths of doctrine of the New Church, because "the New Jerusalem" means the New Church in respect to doctrine from the Word; and therefore its "wall" and foundations" of the wall, can mean nothing else than the external of the Word, which is the sense of the letter; for it is from this sense that doctrine exists, and the church by means of doctrine; while the external of the Word is like a wall with its foundations, which encloses and protects a city. Of the New Jerusalem and its foundations we read in the Apocalypse:
An angel measured the wall of the city Jerusalem, an hundred and forty and four cubits, which was the measure of a man, that is, of an angel. And the wall had twelve foundations adorned with every precious stone. The first foundation was jasper; the second, sapphire; the third a chalcedony; the fourth, emerald; the fifth, sardonyx; the sixth, sardius; the seventh, chrysolite; the eighth, beryl; the ninth, topaz; the tenth, chrysoprasus; the eleventh, jacinth; the twelfth, amethyst (21:14, 17-20).
The wall had twelve foundations formed of as many precious stones, because the number "twelve" signified all things of truth from good; so here all things of doctrine. But this and what precedes and follows in this chapter, may be seen explained in detail and confirmed by parallel passages from the prophetic Word, in our Apocalypse Revealed.