The first altar mentioned in the Word was the one built by Noah after he came out of the ark, after being saved from the great flood. On that altar, he sacrificed clean animals to the Lord.

Mountains represent the Lord because of their height; we need to raise our thoughts above worldly things when "talking" with the Lord. An altar is a small artificial mountain. When it's used in worship, it can call to mind this raising of thought. The fire and smoke that rise from an altar are symbolically being sent to the Lord.

Most altars were made from unhewn stones. Stones represent truths. Unhewn stones - ones that have not been shaped by men - represent truths from the Word, truths that have not been adulterated.

The clean beasts to be sacrificed represent good things, charitable acts done because they are right. The clean birds represent thoughts about doctrine and actions, and about what is right. Presenting these things is an acknowledgment that we have them from the Lord, and a giving thanks to Him for them.

In the Israelitish Tabernacle, the altar of burnt offering represented the acknowledgment of good and the altar of incense that of truth. For this reason this larger altar, which was outside by the door, was made of brass which signifies natural good, while the altar of incense was made of gold, which signifies love to the Lord from whom comes truth.

895. 21:9 Then one of the seven angels who had the seven bowls filled with the seven last plagues came to me and talked with me, saying, "Come, I will show you the bride, the Lamb's wife." This symbolizes an influx and revelation from the Lord from the inmost of heaven regarding the New Church, which will be conjoined with the Lord through the Word.

One of the seven angels who had the seven bowls filled with the seven last plagues and who talked with John means the Lord flowing in from the inmost of heaven and speaking through the inmost of heaven, here revealing the things that follow. That this angel means the Lord is apparent from the exposition of chapter 15, verses 5-6, which says:

After these things I looked, and behold, the temple of the tabernacle... in heaven was opened. And out... came the seven angels having the seven plagues... (Revelation 15:5-6)

This symbolically means that the inmost of heaven appeared, where the Lord is present in His holiness and in the Law contained in the Ten Commandments, as may be seen in nos. 669, 670 above.

It is apparent also from the exposition of chapter 17:1, which says:

Then one of the seven angels who had the seven bowls came and spoke with me, saying..., "Come, I will show you the judgment of the great harlot...." (Revelation 17:1)

This symbolizes an influx and a revelation from the Lord from the inmost of heaven about the Roman Catholic religion, as may be seen in nos. 718, 719 above.

It is apparent from this that one of the seven angels who had the seven bowls filled with the seven last plagues coming to John and talking with him means the Lord flowing in from the inmost of heaven; that coming to him and showing him symbolizes a revelation; and that the bride, the Lamb's wife, symbolizes the New Church, which will be conjoined with the Lord through the Word, as in no. 881.

This church is called a bride when it is being established, and a wife after it has been established. Here it is called a bride and wife because it is of a surety going to be established.