904. 21:15 And he who talked with me had a gold reed to measure the city, its gates, and its wall. This symbolically means that to people who possess the goodness of love, the Lord grants a faculty for understanding and knowing the nature of the Lord's New Church as regards its doctrine and its introductory truths, and as regards the Word from which they are drawn.
He who spoke with me symbolizes the Lord speaking from heaven, because it was an angel speaking, one of the seven angels who had the seven bowls mentioned in verse 9, who means the Lord speaking from heaven (no. 895). A reed symbolizes a power or ability springing from the goodness of love - a reed symbolizing power or ability (no. 485), and gold the goodness of love (nos. 211, 726). To measure means, symbolically, to learn the character of a thing, thus to understand and know it (no. 486). The city, the holy Jerusalem, symbolizes the church in respect to its doctrine (nos. 879, 880). Its gates symbolize concepts of truth and goodness from the Word's literal sense, which are truths and goods owing to the spiritual life in them (no. 899). And the wall symbolizes the Word in its literal sense from which the doctrine and concepts come (no. 898).
It is apparent from this that "he who talked with me had a gold reed to measure the city, its gates, and its wall," symbolically means that to people who possess the goodness of love, the Lord grants a faculty for understanding and knowing the nature of the Lord's New Church as regards its doctrine and its introductory truths, and as regards the Word from which they are drawn.
(Odkazy: Apocalypse Revealed 879-880)
 These symbolic meanings cannot be seen at all in the literal sense, for one sees in it only that an angel speaking with John had a gold reed with which to measure the city and its gates and wall. But even so, that these words contain another meaning, a spiritual meaning, is clearly apparent from the fact that the city Jerusalem does not mean a real city, but the church. Consequently everything said about Jerusalem as a city symbolizes such things as have to do with the church, and everything having to do with the church is, in itself, spiritual.
Such a spiritual meaning is present also in what is said in chapter 11 above, where we are told the following:
I was given a reed like a measuring rod. And the angel stood by, saying, "Rise and measure the temple of God, the altar, and those who worship there." (Revelation 11:1)
A similar spiritual meaning is present, too, in everything that the angel measured with a reed in Ezekiel 40; 41; 42; 43; 44; 45; 46; 47; 48. Also in these verses in Zechariah:
I raised my eyes and looked, and behold, a man with a measuring line in his hand. So I said, "Where are you going?" And he said to me, "To measure Jerusalem, to see what its width is and what its length." (Zechariah 2:1-2)
Indeed, such a spiritual meaning is present in everything connected with the Tabernacle and in everything connected with the Temple in Jerusalem, whose measurements we are told, and also in the measurements themselves. And yet nothing of this can be seen in the literal sense.