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.

4977. 'And he put him in charge over his house' means that this good applied itself to that factual knowledge. This is clear from the meaning of his 'lord', who put him in charge, as good, dealt with above in 4977, and from the meaning of 'putting him in charge over his house' as applying itself to it - to factual knowledge or natural truth. This meaning is evident from what follows, where it says that 'whatever he had he gave into his hand', meaning that all belonging to that good was seemingly subject to the other's power and control. For good is the lord and truth its minister, and when it says that the lord put the minister in charge, that is, that good put truth in charge, the meaning in the internal sense is not that the lordship ceased to rest with that good but that it applied itself to the truth. For in the internal sense one perceives what a thing really is, whereas the sense of the letter presents it in the form of an appearance. The lordship always rests with good, but good applies itself so that truth may be joined to it.

[2] While a person is governed by truth, as happens before he has been regenerated, he knows scarcely anything at all about good. For truth flows in by an external route, or that of the senses, whereas good flows in by an internal route. Before he has been regenerated a person is aware of that which flows in by the external route, but not of that which comes by the internal one. Consequently unless in that state which comes first the lordship seemed to be given to truth, that is, unless good applied itself to it, that truth could never become attached to this good as its own. This is the same factor as has been presented many times before - that truth seemingly occupies the first place, that is, it is so to speak the lord, while a person is being regenerated, but that good plainly occupies the first place and is the lord once he has been regenerated, for which see 3539, 3548, 3556, 3563, 3570, 3576, 3607, 3701, 4925, 4926, 4928, 4930.