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.

8643. 'And Jethro, the priest of Midian' means Divine Good. This is clear from the representation of 'Jethro, the priest of Midian' as the good of the Church which is guided by the truth that goes with simple good, dealt with in 7015, but at this point Divine Good, because 'Moses', whose father-in-law he was, represented Divine Truth; for when the son-in-law represents truth, the father-in-law represents good, that is, a higher level of good since he is his wife's father. The reason why Divine Good is represented at this point by 'Jethro' is that the subject in this chapter is the arranging of truths into order with a member of the spiritual Church, which is done by Divine Good working through Divine Truth. For whenever arrangement into order takes place it is done by good working through truth.

[2] Truths are arranged into order in this way with a member of the spiritual Church when his actions begin to be governed no longer by truth but by good. This state is his second state, which arises after he has undergone temptations. When truth governs his actions he undergoes temptation, to the end that the truths with him may become firmly accepted. Once they have been firmly accepted they are arranged into order by the Lord; and once they have been arranged into order the person enters the second state, in which the truths are in his will and in his actions. As a result of this they become part of his life, and are called forms of good. This arranging of truths into order is the subject below.