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.

1610. That 'I will make your seed as the dust of the earth' means being multiplied beyond measure is clear without explanation. Here it is said that his seed would be made as 'the dust of the earth', in other parts of the Word as 'the dust of the sea', and in yet other parts as 'the stars of heaven'. Each of these phrases has its own particular meaning. 'Dust of the earth' has regard to those things that are celestial, for, as shown already, 'the earth' means the celestial aspect of love; 'dust of the sea' has regard to those things that are spiritual, for 'the sea', as has also been shown, means the spiritual aspect of love; while 'as the stars of heaven' means both but in a higher degree. And because these things cannot be numbered they therefore became common expressions to describe growth and multiplication beyond measure.

[2] The statement that his seed, that is, the faith that is the expression of love, or simply love, was to be multiplied beyond measure means in the highest sense the Lord, and in particular His Human Essence, for the Lord as regards the Human Essence is called 'the seed of the woman', dealt with in 256. When the Lord's Human Essence is meant, the infinite celestial and spiritual is understood by the words 'multiplied beyond measure'; but when faith that is the expression of charity, or simply charity, among the human race is meant by 'the seed', the multiplication without measure of that seed in everyone who leads a charitable life is understood. Such multiplication takes place in the next life with everyone who leads a charitable life. With him the multiplication of charity and of the faith deriving from it, together with their associated happiness, is so great that one can only describe it as being beyond measure and defying description. When the human race is meant by 'the seed', the multiplication of this in the Lord's kingdom is also beyond measure - not only from those who are inside the Church, and their children, but also from those who are outside the Church, and their children. Consequently the Lord's kingdom or heaven is boundless. That boundlessness will in the Lord's Divine mercy be spoken of elsewhere.