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.

63. (Verse 13) And in the midst of the seven lampstands one like unto the Son of man. That this signifies the Lord, from whom is the all of heaven and of the church, is evident from the signification of "in the midst," as denoting in the inmost (see Arcana Coelestia 1074, 2940, 2973); and, because all things proceed from the inmost as light from the centre into the circumferences, therefore, "in the midst," signifies from whom. This is evident also from the signification of the seven lampstands, as denoting the New Heaven and the New Church (concerning which see above, n. 62); and from the signification of the Son of man, as denoting the Lord as to the Divine Human, and also as to Divine truth, because this proceeds from His Divine Human. From these considerations it is evident that the Lord appeared in the midst of seven lampstands, because from Him proceeds the all of heaven and of the church; for the good of love and the good of faith constitute heaven and the church, and that these are from the Divine is known in the Christian world, and because they are from the Divine, they are from the Lord, because the Lord is the God of heaven, and because the Divine of the Lord makes heaven (see the work, Heaven and Hell 2-6, and n. 7-12; and that this is His Divine Human, n. 78-86).

[2] That by the Son of man is meant the Lord as to the Divine Human, and also as to Divine truth, because Divine truth proceeds from His Divine Human, is evident from those passages in the Word where mention is made of the Son of man. Thus in John:

The multitude said unto Jesus, "How sayest thou that the Son of man must be lifted up? who is this Son of man? Jesus answered them, Yet a little while the light is with you; walk while ye have the light, lest darkness come upon you. While ye have the light believe in the light, that ye may be sons of light" (12:34-36).

From these words it is clear that by the Son of man is signified the same as by light; for when they inquired, "Who is this Son of man?" the Lord answered that He was the light in which they should believe. (That light is the Divine truth proceeding from the Divine Human of the Lord, may be seen in the work, Heaven and Hell 126-140; and in The Doctrine of the New Jerusalem 49; thus also that the Son of man is the Divine truth.) It is said in Luke:

[3] "Blessed are ye when men shall hate you for the Son of man's sake" (6:22).

For the Son of man's sake is for the sake of the Divine truth which proceeds from the Lord. Divine truth is the all of faith and love to the Lord; and because they who are evil deny those things, and they who deny also hate them, and the good acknowledge them, therefore it is said, that these latter are blessed. Again, in the same:

[4] "The days will come, when ye shall desire to see one of the days of the Son of man, but ye shall not see it. Then they shall say to you, Behold here, or behold there; go not away, nor follow them" (17:22, 23).

To desire one of the days of the Son of man, is to desire something of genuine Divine truth. The end of the church is there meant, when there will be no longer any faith, because no charity, at which time all Divine truth will perish; and because Divine truth is signified by the Son of man, therefore it is said, "Then shall they say, Behold here, or behold there; follow them not." And in the same:

[5] "When the Son of man cometh, shall He find faith on the earth?" (18:8);

that is, when Divine truth shall be revealed out of heaven, it will not be believed. The Son of man, in this place also, is the Lord as to Divine truth; the coming of the Lord is the revelation of Divine truth at the end of the church. (See Arcana Coelestia 3900, 4060.)

[6] And in Matthew:

"As the lightning cometh out of the east, and shineth even unto the west; so shall the coming of the Son of man be. Then shall appear the sign of the Son of man in heaven; and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven, with power and glory" (24:27, 30).

(That by the coming of the Lord in the clouds of heaven, is there signified the revelation of Divine truth at the end of the church, may be seen above, n. 36.)

[7] And in the same:

"I say unto you, Hereafter ye shall see the Son of man sitting on the right hand of power, and coming in the clouds of heaven" (26:64).

And in Luke:

"Hereafter shall the Son of man sit on the right hand of the power of God" (22:69).

The Son of man is the Lord as to the Divine Human, and as to Divine truth proceeding from It; to sit on the right hand of power, means that He has omnipotence; its being said that they should see this now, means, that Divine truth was in its omnipotence when the Lord in the world had conquered the hells, and reduced to order all things there and in the heavens, and that thus those would be saved who should receive Him in faith and love. (See Arcana Coelestia 9715. That to sit on the right hand denotes omnipotence, may be seen Arcana Coelestia 3387, 4592, 4933, 7518, 8281, 9133; that all the power of good is by truth, n. 6344, 6423, 8304, 9327, 9410, 9639, 9643. That Divine power itself is by Divine truth proceeding from the Divine Human of the Lord, see n. 6948; that the clouds in which the Son of man will come are the Word in the letter, which is Divine truth in the ultimate of order, see the preface to the eighteenth chapter of Genesis, Arcana Coelestia 4060, 4391, 5922, 6343, 6752, 8443, 8781; and that glory is the Divine truth itself, such as it is in the internal sense of the Word, see n. 4809, 5922, 8267, 9429.)

[8] From these considerations it is now evident what is signified by these words in the Apocalypse:

"I saw, and behold a white cloud, and upon the cloud one sat like unto the Son of man, having on his head a golden crown" (14:14).

And in Daniel:

"I saw in the visions of the night, and behold, one like the Son of man came with the clouds of the heavens" (7:13).

Because all judgment is executed from truth, therefore it is said, that it is given to the Lord "to execute judgment, because he is the Son of man" (John 5:27); and that "the Son of man shall render to every one according to his deeds" (Matthew 16:27); and that "when the Son of man shall come, he shall sit upon the throne of his glory, and shall judge" (Matthew 25:31).

[9] And again in Matthew, it is said:

"He who soweth the good seed is the Son of man; the field is the world; the good seed are the sons of the kingdom, but the tares are the sons of the evil" (13:37, 38).

The good seed is Divine truth, therefore it is said that the Son of man soweth it; the sons of the kingdom are Divine truths in heaven and the church; for son denotes truth (see Arcana Coelestia 489, 491, 533, 1147, 2623), and, in an opposite sense, falsity, which also is the son of evil.

[10] In the same:

"The Son of man hath not where to lay his head" (8:20);

by which is signified, that Divine truth had not a place anywhere, or with any man, at that time. Again it is said, that the Son of man would suffer and be put to death (Matthew 17:12, 22; 26:2, 24, 45; Mark 8:31; 9:12, 31); by which is signified, that thus they would treat Divine truth, consequently the Lord, who was Divine truth itself, as He also teaches in Luke:

"The Son of man must first suffer, and be rejected of this generation" (17:25).

[11] In Jeremiah:

"No man [vir] shall dwell there; neither shall a son of man [hominis] abide there" (49:18, 33).

In the same:

In the cities "no man shall dwell, nor shall a son of man pass through them" (51:43).

He who is not acquainted with the spiritual sense of the Word, believes that by cities here are meant cities, and that by man, and by a son of man, are meant a man and a son; also, that the cities were thus to be desolated, so that no one should be in them; but it is the state of the church as to the doctrine of truth which is described by those words; for cities denote the doctrinals of the church (as may be seen, Arcana Coelestia 402, 2449, 3216, 4492, 4493); and man is the essential truth thereof, conjoined with good (see n. 3134, 7716, 9007); thus the Son of man is truth. Because the Son of man signified Divine truth proceeding from the Lord, therefore the prophets also, through whom it was revealed, were called "sons of man," as Daniel (8:17); and Ezekiel (2:1, 3, 6, 8; 3:1, 3, 4, 10, 17, 25; 4:1, 16; 8:5, 6, 8, 12, 15; 12:2, 3, 9, 18, 22, 27). As most things in the Word have also an opposite sense, so also has the signification of a son of man, which in that sense denotes falsity opposed to truth. Thus in Isaiah:

"What art thou, that thou fearest man? he dies; and a son of man? he is as grass" (51:12).

And in David:

"Place not your trust in princes, in a son of man, with whom there is no salvation" (Psalm 146:3).

Princes denote primary truths (see Arcana Coelestia 2089, 5044); thus, in an opposite sense, primary falsities; and son of man denotes falsity itself.