Britannica –
“The traditional founder and head of the Jewish priesthood, who, with his brother Moses, led the Israelites out of Egypt. The figure of Aaron as it is now found in the Pentateuch is built up from several sources of traditions. In the Talmud and Midrash; he is seen as the leading personality at the side of Moses. He has appeared in different roles in Christian thought.
Aaron is described in the Old Testament book of Exodus as a son of Amram and Jochebed of the tribe of Levi, three years older than his brother Moses. He acted together with his brother in the desperate situation of the Israelites in Egypt and took an active part in the Exodus. Although Moses was the actual leader, Aaron acted as his “mouth.” The two brothers went to the pharaoh together, and it was Aaron who told him to let the people of Israel go, using his magic rod in order to show the might of Yahweh. When the pharaoh finally decided to release the people, Yahweh gave the important ordinance of the Passover, the annual ritual remembrance of the Exodus, to Aaron and Moses. But Moses alone went up on Mt. Sinai, and he alone was allowed to come near to Yahweh. Moses later was ordered to “bring near” Aaron and his sons, and they were anointed and consecrated to be priests “by a perpetual statute.” Aaron’s sons were to take over the priestly garments after him. Aaron is not represented as wholly blameless. It was he who, when Moses was delayed on Mt. Sinai, made the golden calf that was idolatrously worshiped by the people.”
Encyclopaedia Britannica Online, http://www.britannica.com/EBchecked/topic/277/Aaron (accessed June 24, 2009)