Gold
Gold means good, and just as gold was the most precious metal known to ancient mankind so it represents the good of the highest and wisest of the angels. These angels foremostly love the Lord, and because they do they act from that love at all times. So the things they do are from love or as the writings for the new church often say, their acts are "goods of love". This is what gold represents. As soon as God planted the garden of Eden, He created a river in it, to water it. This river went out and branched into four, the first branch mentioned, Pishon, encompassed the "…land of Havilah, where there is gold… and the gold…is good". Another mention of gold comes in Exodus where the Lord is telling Moses how to make the Tabernacle. If you pay attention you will see that inside the tabernacle the main thing you see is gold, the boards of the wall are covered with it and all the furniture is either wood covered completely with gold, or is made of solid gold. Then at the end of the Word the holy city descends from God and it is made of gold, "gold like unto clear glass" good of love that can be clearly and completely understood. And it has its river. This is a promise from the Lord that we can come into a state similar to that of the garden of Eden, if we follow Him so as to come into love for Him, and act from that love.
