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.

920. And cast it into the great wine-press of the anger of God, signifies the falsification of the Word as to all spiritual truth, and consequent damnation, because there is no spiritual good, which is charity. This is evident from the signification of "wine-press" as being the bringing forth of truth from good; for "clusters" and "grapes," which were put into the wine-press, signify spiritual good, and "wine" which is produced, signifies truth from that good (See above, n. 220, 376). As "the wine-press" signifies the bringing forth of truth from spiritual good, so in the contrary sense it signifies the bringing forth of falsity from evil. For in like manner as good brings forth truth, so evil opposite to good, brings forth falsity. "Wine-press" signifies here the falsification of the Word as to all spiritual truth, because it is called "the great wine-press of the anger of God," and "the anger of God" signifies man's contempt for truth and good and his rejection of it, and the full rejection of it is the falsification of the sense of the letter of the Word even to the destruction of spiritual truth, that is, of the Divine truth which is in heaven. That this falsification closes heaven may be seen n. 888. Moreover, those who are in evil (and all are in evil who are not in the good of charity) cannot do otherwise than bring forth falsities; for as good brings forth truths so evil brings forth falsities. "The great wine-press of the anger of God" signifies also damnation, because this is a consequence, and because the terms "anger of God" and "great wine-press" are used. That this is what a "wine-press" signifies will be confirmed from the Word in the next article.

[2] Here a few words shall be said about the bringing forth of truth from good, and also of falsity from evil, which is signified by "wine-press" in the spiritual sense. The origin and cause of such bringing forth is that all good is from love, and that which is loved gives delight; and as delight is grateful and pleasing, that which is of the love man thinks about with delight and also confirms. And since love with its delight constitutes the life of man, when man thinks from love and its delight he thinks from self and from his life. That this is so can be clearly seen from men after death, when they have become spirits; for then, when they think from self, they can think in no other way than from their love, since their whole life is their love. Since, therefore, good is from love and truth is from thought, it is clear how truth is brought forth from good.

[3] The same that has been said of good and truth can be said of the will and understanding; for as all good is from the love it is from the will, and as all truth from good is from the thought it is from the understanding; for the will loves, and the understanding thinks. The same that has been said of good and truth can be said of heat and light; for spiritual heat is the love that enkindles the will, and the spiritual light is the truth that enlightens the understanding. For all love, which is from the will, presents an effigy of itself in the light of the understanding, where it recognizes itself and wishes to see itself, because it loves itself; and this is why man thinks what he loves.

[4] The same that has been said of the bringing forth of truth from good can be said of the bringing forth of falsity from evil. For all evil is from the love, and therefore it loves falsity; and evil is from the will, and falsity is from the thought from evil. This has been said because "wine-press" signifies in the spiritual sense the bringing forth of truth from good, also the bringing forth of falsity from evil. "The great wine-press of the anger of God" signifies also the falsification of the word, because the falsification of the Word is the bringing forth of falsity from evil; for evil is what falsifies, since evil loves the idea of itself in the thought, and the thought, that it may persuade, wishes to find confirmation of the evil in the Word.