Hebrews 5:4

And no one takes this honor for himself, but only when called by God, just as Aaron was.

Aaron and Moses may have been brothers but they each had a very different childhood. Aaron was raised by father Amram and mother Jochebed, who was also Amram’s aunt (Exodus 6:20). Aaron escaped Pharaoh’s edict by little and learned to live as a slave making bricks in the hot sun for Pharaoh’s building projects. Moses was raised in the cool shade of Pharaoh’s palace; he was educated, and became an army officer and a skillful international diplomat.

Through the story of Moses’ and Aaron we are given the definition of a prophet. Moses felt inadequate to speak to the people of God, so Hashem said of Moses’ brother, He shall speak for you to the people, and he shall be your mouth, and you shall be as God to him (Exodus 4:16). Aaron’s job was to be Moses’ mouth not only to Hashem’s children, but also to the incredulous world of his day, And the LORD said to Moses, "See, I have made you like God to Pharaoh, and your brother Aaron shall be your prophet (Exodus 7:1). According to these statements, the definition of a prophet: is someone who has the ability to effectively communicate God’s messages to a desired audience.

Later Aaron was given another function to execute for the people of Hashem. He became High-Priest. As a High-Priest, he continued his function as Moses’ mouth-piece and executive, but people came to him to find the will of God, which Aaron communicated through the use of the Urim and Thummim. These were the stones on Aaron’s breastplate by which he judged Israel, And in the breastpiece of judgment you shall put the Urim and the Thummim, and they shall be on Aaron's heart, when he goes in before the LORD. Thus Aaron shall bear the judgment of the people of Israel on his heart before the LORD regularly (Exodus 28:30). When Aaron was speaking by the Spirit the right one lit. For the Hebrews, prophecy was a very pragmatic matter. The Children of Israel didn’t always obey the Word they heard, but there was very little doubt as to who said it.

As a High-Priest, Aaron led the priest-hood. The priesthood dealt with the sins of Israel. Though punishments and restitutions were to be executed as a result of sinful acts, offerings also had to be brought to the Temple for the restitution of fellowship with Adonai which was broken because of sin. The sinful person killed the animal, not the priest. The priest only brought the blood to the altar. Once a year also, Aaron the High-Priest brought an offering for the whole nation on Israel in the Holy of Holies. In a certain sense, the function of the priesthood served to remind us of our sinful state; it convicted of sin. In talmudic wrtings, Aaron is also known the peacemaker (Psalms 133).

Aaron’s role was therefore that of a communication medium between us and Hashem, one that also reminded us of our sin. How like the Ruach-HaKodesh, the Holy Spirit Aaron was!