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.

10021. 'And you shall bring the young bull' means a state in which the natural or external man, as this is in its infancy, applies itself. This is clear from the meaning of 'bringing near' as effecting presence and togetherness, dealt with in 9378, 9997, 10001, and also application, 8439, at this point applying oneself to purification and to the reception of goodness and truth from the Divine, because by this sacrifice and by sacrifices generally such application is meant; and from the meaning of 'the young bull' as the good of charity and innocence in the natural or external man, dealt with in 9391, thus the external or natural man as this is in its infancy, for at this time the good of innocence reigns there. While in this state the external man is also in a state of applying itself to purification and to the reception of goodness and truth from the Divine.

[2] Since these matters are now the subject in the internal sense the nature of them must be mentioned. When a person is being regenerated, which happens when he has reached adult life, he is first let into a state of innocence, but a state of external innocence almost like young children's; for their innocence is an external innocence that resides in lack of knowledge. This state serves as the basis for new life while the person is being regenerated; for at this time also the person is a young child so to speak, in that while being regenerated he is conceived anew, born, becomes a young child, and grows up, all of which is accomplished through truth implanted in good. Also to the extent that he comes at this time into authentic good he passes on into the good of internal innocence, which is innocence residing in wisdom. And since the regeneration of a person is an image of the glorification of the Lord, it is evident that the manner in which the Lord glorified Himself, that is, made Divine His Human, is the same. For the subject in the internal sense of this chapter is the glorification of the Lord, 9985; but since the glorification of the Lord's Human is beyond understanding the likeness or image of it must be used to explain it and so give some idea of it. These things have been mentioned first so that people may know what to understand by purification and by reception of goodness and truth, and by joining together the things that are meant by sacrifices generally, and at this point specifically by the sacrifices offered at the consecration of Aaron and his sons to the priestly office.

The regeneration of a person is an image of the glorification of the Lord, see 3138, 3212, 3296, 3490, 4402, 5688.

Young children's innocence is an external innocence, and it resides in lack of knowledge, 2305, 2306, 3494, 3504, 4563, 4797, 5608, 9301.

A person who is being regenerated is conceived anew, born, becomes a young child, then an older one, and grows up, 3203.

The innocence of early childhood serves as a basis, 2780, 3183, 3994, 4797, 5608, 7840.

Cognitions or knowledge of truth and good are implanted in the innocence which belongs to early childhood as their basis, 1616, 2299, 3504, 4797.

The innocence of those who have been regenerated is an internal innocence, and it resides in wisdom, 1616, 3494, 3994, 4797, 5608, 9301, 9938.

The difference between external innocence which young children possess and internal innocence which the wise possess, 2280, 4563, 9301.

The nature of the difference becomes clear from the upbringing and regeneration of children in the next life, dealt with in 2289-2309.

All the good of the Church and heaven holds innocence within itself, and without it good is not good, 2736, 2780, 6013, 7840, 7887, 9262.

What innocence is, 3994, 4001, 4797, 5236, 6107, 6765, 7902, 9262, 9936.