In the previous page we have seen that the God of Israel was thought in masculine terms due to His transcendence. It's therefore follows that human beings representing God would have to be of the male gender. God told Moses:
"Have your brother Aaron, and with him his sons, brought to you, from among the Israelites, that they may be my priests: Nadab and Abihu, Eleazar and Ithamar, Aarons sons." (Ex 28:1)
Aaron and his sons were consecrated by Moses before Tabernacle. This ceremony is described in Ex. 29. After a washing, Aaron was robed with special vestments and anointed with special oil on his head. Moses was instructed to clothe his sons with tunic, gird them with sashes and tie skullcaps on their heads." Thus shall the priesthood be theirs by a perpetual statute, and thus shall you install Aaron and his sons." (Ex 29:9)
This was followed by the sacrifice of a bull upon which they lay their hands. Blood was applied to the altar and the bull burned as a PURIFICATION OFFERING. Two rams were also sacrificed. The first ram was sacrificed and its blood plashed on the side of the altar. The blood of the second ram sacrificed was applied to the right ear, right hand tomb and right foot toe of each priest. Some parts of this ram were burned, the rest given to the priests as their portion along with bread and oil cakes.
A descendant of Aaron who wanted to become a priest had to be holy or set apart from other people. He could not have any physical deformity; he could not marry a divorced woman or a prostitute; he could not shave his head or touch a dead body. He had to be more holy than the rest of the Jews. To us this may appear as discrimination against the handicapped but in God's plan the Levitical priesthood was meant to foreshadow Christ.
The priests offering sacrifices could only use animals without blemish and of the mail gender, (bulls, lambs, goats and rams). Why? In God there is no past, present and future. He sees everything as present. Animals symbolized the sacrifice of Christ without the blemish of Sin who was to become Incarnate and sacrificed for the sins of mankind.
Actually the whole tribe of Levi, the third son of Jecob, were set aside to serve God but only the descendants of Aaron were actually priests who "Could offer sacrifices for the people, burn incense on the altar, and teach the law, whereas the other Levites were employed in more menial tasks, such as the housekeeping of the tabernacle, keeping oil in the lamps, transporting the Ark of the Covenant, taking down and setting up the tabernacle when moving, and related tasks in assisting the priests." (Num. 3:510; 18:17; 1 Chr. 23:2732). They could also serve as singers and musicians in the temple service.