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.

3735. 'And clothing to wear' means being joined to Divine Truth. This is clear from the meaning of 'clothing' as truth, dealt with in 1073, 2576, Divine Truth here since the Lord is the subject; and from the meaning of 'wearing' as making it one's own and being joined to it. As for the nature of the internal sense of the Word, that becomes clear from these and all other details; that is to say, when the sense of the letter refers to bread and to clothing, and also when it does so within historical narrative, as here in 'If God will give me bread to eat and clothing to wear', the angels present with a person at the time have no thought at all of bread but of the good of love, and in the highest sense, of the Lord's Divine Good. Nor do they have any thought at all of clothing but of truth, and in the highest sense, of the Lord's Divine Truth. To them such things as are referred to in the sense of the letter are simply objects for thought regarding heavenly and Divine matters, for such things are vessels existing in the ultimate degree of order.

[2] So when with holiness of mind a person thinks about bread - for example, when he thinks about the bread in the Holy Supper, or about the daily bread in the Lord's Prayer - that thought which he has about bread serves the angels present with him as an object for thought regarding the good of love which comes from the Lord. For the angels do not take hold of anything at all of the person's actual thought concerning bread, but instead their thought concerns good; for such is the correspondence between the two. It is similar when with holiness of mind a person thinks about clothing. The angels' thought in that case concerns truth. So it is with everything else in the Word. From this the nature of the joining together of heaven and earth by means of the Word becomes clear; that is to say, the joining together is such that when with holiness of mind anyone reads the Word he is joined by means of such correspondences more closely to heaven, and through heaven to the Lord, even though that person's thought is concerned solely with things in the Word which are stated in the sense of the letter. His holiness of mind at that time is the product of the influx of celestial and spiritual thoughts and affections such as exist with angels.

[3] So that such influx might exist and from that influx man might be joined to the Lord, the Lord has instituted the Holy Supper where it is explicitly stated that the Lord is the bread and wine. For the Lord's body means His Divine love, and the reciprocal love in man, love such as exists with celestial angels, while His blood in a similar way means His Divine love, and the reciprocal love in man, but love such as exists with spiritual angels. From this it is evident how much of the Divine there is within every individual part of the Word, though man does not know what that Divine content is or the nature of it. People however who, while in the world, have led a good life enter after death into cognitions and a perception of all those things, for at that time they cast off earthly and worldly things and take to themselves heavenly ones, and have, like angels, spiritual and celestial ideas.