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.

39. 11. (The solitude of Jerusalem is described in direful terms, that to the sole of the foot there is no soundness (Isaiah 1:6-9).

The worship of these things is vanity unless you have cleansed yourselves from evil (Isaiah 1:11-18).)

The restoration of all things by the redemption, and then the salvation of the faithful and the condemnation of the unfaithful, is described (Isaiah 1:25-31).

And it shall come to pass in the last of the days that the mountain of Jehovah shall be established because the Word of Jehovah shall be from Jerusalem (Isaiah 2:2-6). It treats of the restoration of all things through the New Church.

Jehovah alone shall be exalted in that day (Isaiah 2:11, 17).

The restoration of all things through the New Church, which there is Jerusalem, where everyone is written unto life: and it is said, In that day shall the branch of Jehovah be for beauty and glory (Isaiah 4:1 to the end).

(That He would destroy the vine, because it did not bring forth grapes, but wild grapes; I will bring it to desolation, the house to devastation; because they regard not the work of Jehovah (Isaiah 5:3-15).)

A curse upon them, because they call good evil and evil good, and put darkness for light and light for darkness, since they have rejected the law of Jehovah, and despised the saying of the Holy One of Israel. He shall roar against him in that day like the roaring of the sea; and if one look unto the land, behold darkness, anxiety, and the light shall be darkened in the ruins thereof (Isaiah 5:18-30).

That the Lord will appear in the Word; the Lord is meant by "Adonai," and by "holy, holy, holy Jehovah of hosts," by "the Seraphim from above him" (Isaiah 6:1-8).

(Devastation is next treated of because they do not wish to understand the truth; that the cities therefore will be devastated, and the land will be brought back to solitude (Isaiah 6:9-13).)

(In that day Jehovah shall hiss for the fly that is in the uttermost part of the rivers of Egypt, and for the bee that is in the land of Assyria; and they shall come and shall rest in the rivers of desolation (Isaiah 7:18-19).)

In that day shall the Lord shave the head and the hair of Assyria; He shall also consume the beard (Isaiah 7:20). The consummation.

In that day every place shall be for the brier and the thorn (Isaiah 7:23-24). The consummation.

What will ye do in the day of visitation and of devastation which shall come from far? to whom will ye flee for help? The devastation there is described by the pride of their own intelligence (Isaiah 10:3-19), further (Isaiah 10:23-34). And it is said that Jehovah bakes a consummation and decision in the whole earth (verse 23).

Howl ye; for the day of Jehovah is at hand, it will come as a devastation from Shaddai. Behold the day of Jehovah cometh, cruel with indignation and with wrath to lay thy land waste; and He shall destroy the sinners thereof out of it. For the stars of the heavens and their constellations shine not with their light, the sun is darkened at his rising, and the moon shall not cause her light to shine (Isaiah 13:6-10). Therefore I will shake heaven, and the earth will tremble in the indignation of Jehovah of Hosts, in the day of the wrath of anger (13:13). There it treats of the vastation of Babylon.