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.

51. Each Community Is a Heaven in Smaller Form and Each Angel a Heaven in Smallest Form

The reason each community is a heaven in smaller form and each angel a heaven in smallest form is that the activity of love and faith is what makes heaven. This good activity is in every community of heaven and in every angel of a community. It does not matter that this activity is different and distinctive everywhere, it is still the activity of heaven. The only difference is that heaven has one activity here and another there. So whenever anyone is raised into any community of heaven, they say that he or she has arrived in heaven. They say of those who are there that they are in heaven, each in his or her own. All the people who have arrived in the other life realize this; so individuals who are standing outside or below heaven and looking off into the distance where there is a gathering of angels say that heaven is there - and over there as well.

It is rather like the situation of officials and functionaries and servants in a royal palace or court. Even though they live individually in their dwellings or in their rooms, some higher than others, still they are in a single palace or a single court, each one involved in a particular function in the service of the king. We can see from this what is meant by the Lord's saying that "in my Father's house there are many dwellings" (John 14:2) and by "the stories of heaven" and the "heavens of heavens" in the prophets.