On the eighth day of consecration—the first of Nisan—Aaron was about to offer his first sacrifice as high priest. Then he froze. The Targum Jonathan says he "saw at the corner of the altar the form of the calf." The Golden Calf. His sin, staring back at him from the very altar where he was supposed to serve God.
Moses had to talk him through it: "Take courage, and go near to the altar, fearing not." This entire scene—Aaron's terror, Moses's encouragement, the phantom calf—is absent from the Hebrew Bible. The Targum invented it to explain a theological problem: how could the man who built an idol become the one who atoned for idolatry?
The Targum also adds that each sacrificial animal carried symbolic meaning. The calf for Aaron's sin offering was chosen "that Satan may not accuse thee concerning the calf that thou madest at Horeb." The ram recalled "the righteousness of Isaac whom his father bound as a ram on the mountain of worship." The goat for the people's offering was selected because "Satan resembles him, lest he recount against you the accusation concerning the kid of the goats, which the sons of Jacob killed"—a reference to the brothers dipping Joseph's coat in goat blood (Genesis 37:31).
Every animal was a counter-argument against heavenly prosecution. The Targum turns the inauguration of the priesthood into a courtroom drama, with sacrifices serving as legal briefs against the Accuser.
When the ceremony concluded, the Shekinah (the Divine Presence) did not appear. Aaron was "ashamed." Only after Moses and Aaron prayed together inside the Tabernacle did fire descend from heaven and consume the offering. The people fell on their faces—not from fear, but praise.