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.

27. The Lord is called the Son of man when the subject is redemption, salvation, reformation and regeneration. This is clear from the following:

...the Son of man (came) to give His life a redemption for many. (Matthew 20:28, Mark 10:45)

...the Son of man has come to save..., (and) not...to destroy.... (Matthew 18:11, Luke 9:56)

...the Son of man has come to seek and to save that which was lost. (Luke 19:10)

(The Son of man came) that the world through Him might be saved. (John 3:17)

He who sows the good seed is the Son of man. (Matthew 13:37)

The subject there is redemption and salvation, because these are accomplished by the Lord through the Word, and the Lord therefore calls Himself the Son of man.

The Lord says that “the Son of man has power...to forgive sins” (Mark 2:10, Luke 5:24), that is, to save from them. Also, that He is Lord of the Sabbath, because He is the Son of man (Matthew 12:8, Mark 2:28, Luke 6:5), since He is the Word that He teaches then. Moreover, He says in John:

Labor not for the food which perishes, but for the food which endures to everlasting life, which the Son of man will give you.... (John 6:27)

Food means all the truth and goodness of doctrine drawn from the Word, thus from the Lord.

This, too, is meant by the manna and bread referred to there that descended from heaven, and by the following declaration as well in the same chapter:

...unless you eat the flesh of the Son of man and drink His blood, you have no life in you. (John 6:53)

Flesh, or bread, is the goodness of love gained from the Word, while blood, or wine, is the goodness of faith gained from the Word, both originating from the Lord.

[2] The Son of man has the same symbolism in other places where the Son of man is mentioned. So, for example, in the following:

Foxes have holes and birds...have nests, but the Son of man has nowhere to lay His head. (Matthew 8:20, Luke 9:58)

This means that the Word would have no place among the Jews, as the Lord also says in John 8:37. Nor would they have it abiding among them, because they did not acknowledge Him (John 5:38).

The Son of man means the Lord in relation to the Word as well in the book of Revelation:

(I saw) in the midst of the seven lampstands one like the Son of man, clothed with a long robe and girded about the breasts with a golden girdle. (Revelation 1:13ff.)

Various things in that book represent the Lord as the embodiment of the Word, for which reason He is called the Son of man.

In Psalms:

Let Your hand be upon the man of Your right hand, upon the Son of man whom You made strong for Yourself. Then we will not turn back from You; revive us.... (Psalms 80:17-18)

The man of the right hand here as well is the Lord in relation to the Word, like the Son of man. He is called the man of the right hand because the Lord has power from Divine truth, which is also what the Word is, and He had Divine power when He fulfilled the whole of the Word. That is why He also said that people would see the Son of Man sitting at the right of the Father with power (Mark 14:62).