The Levitical Priesthood
According to Numbers 16:5 the Levitical priests were commissioned by God, separated unto God, and were allowed to approach God. "Then he said to Korah and all his followers: 'In the morning the Lord will show who belongs to him and who is holy, and he will have that person come near him. The man he chooses he will cause to come near him."
The Levitical priesthood began with the tribe of Levi and proceeded through the sons of the family of Aaron, according to Numbers 18:1,8 and Exodus 28:1, which says, "Have Aaron you brother brought to you from among the Israelites, along with his sons Nadab and Abihu, Eleazar and Ithamar, so they may serve me as priests." However, physical blemishes disqualified any male descendant of Aaron, according to Leviticus 21:17-23, from which 21:17 is presented: "The Lord said to Moses, 'Say to Aaron: 'For the generations to come non of your descendants who has a defect may come near to offer the food of his God.'"
The duties of the Levitical priesthood included: the teaching of the Law, Leviticus 10:11; offering the sacrifices, Leviticus chapter 9; maintaining the Tabernacle and the Temple, Numbers 18:3; officiating in the Holy Place, Exodus 30:7-10; inspecting ceremonially unclean persons, Leviticus chapters 13 and 14; they adjudicated disputes, Deuteronomy 17:8-13; they functioned as tax collectors, Numbers 18:21,26; Hebrews 7:5.
Sustenance of the priesthood occurred through the following
vehicles: prescribed portions of the sacrificial offerings, Numbers
18:8-14; one habitual tithe from which tithe a tenth part was
assigned to the priests, Numbers 18:21-24, cf. Lev. 27:30-33,
cf. Numbers 18:26-28; along with thirteen assigned cities, Joshua
21:13-19, which provided a special tithe every third year, Deuteronomy
14:27-29; 26:12; the redemption money for the firstborn in Israel,
Leviticus chapter 27; an assigned portion of the spoils of war,
Numbers 31:25-27; along with the shewbread, Leviticus 24:5-9.
Levitical priests served for 25 years, from age 25 to age 50, according to Numbers 8:24,25.
Other than the family of Aaron, there were three other family lines in the tribe of Levi (Numbers chapter 4): the kohathites, who maintained the furniture, vessels and veil of the Tabernacle; the gershonites, who maintained the coverings, hangings and doors of the Tabernacle; the merarites, who maintained the supports, including the planks bars and cords, of the Tabernacle.
Initially, God had selected the entire nation of Israel to be his priests, according to Exodus 19:5,6; however, after the nation proved to be inadequate as priests, Exodus 32:7-10, the Levites who supported Moses in Exodus chapters 26-28 were selected as God's priests, Numbers 3:5-9.
The apparel of the high priest is cited in Exodus chapter 28. Both the priests and the high priest, except for ceremonial events, dressed as other Jews. At ceremonial events, however, the high priest wore white linen shorts, a white linen coat that came to the hips, a ceremonial belt colored in correspondence to the curtains of the Tabernacle -- white, blue, scarlet, and purple; he also wore a turban-like cap with a golden crown, upon which was inscribed: 'holy to Jehovah.' Additionally, the high priest wore an ephod of blue, beautifully embroidered in the colors cited above; also a breast-plate of gold and cloth, with the urim and the thummim on the shoulders, and twelve stones, each stone representing one of the twelve tribes; each stone was engraved with their names and fastened with a golden clasp.
The sanctification of the high priest and the priests is found in Exodus chapter 29. And the principal duty of the high priest was to officiate on the Day of Atonement, according to Leviticus chapter 16. On the Day of Atonement, the high priest, caparisoned in his ceremonial garments, 'drew near to God;' he entered the Tabernacle (or later the Temple), and sprinkled over the top of the mercy seat the blood of the bullock of the sin offering for himself, Leviticus 16:6,14. After he came forth from the Holy of Holies, he again entered and sprinkled the blood of the goat of the sin offering for the people. Both times he emerged from the Holy of Holies after sprinkling the blood had hamartiological (sin) ramifications: pardon for his personal sins, and pardon for the sins of the people; and in each instance the pardon was based solely upon the 'blood of the sin offering,' which represented Christ on the Cross, Leviticus 16:30.
According to Numbers 20:28, the office of the high priest was transmitted upon death to the oldest living son of the high priest: "Moses removed Aaron's garments and put them on his son Eleazar. And Aaron died there on top of the mountain. Then Moses and Eleazar came down from the mountain." And according to Numbers 25:10-13, God made a covenant with Phinehas, the eldest son of Eleazar, which guaranteed a lasting priesthood with the Aaronic line.
The line switched during Saul ben-Kish's reign; Eli, a descendant of Ithamar, assumed the office of high-priest, however, he functioned only de facto and not de jure (legally). In fact, his descendants were removed from the priesthood because of Eli's failure to censure his sons, I Samuel 2:23-25; 3:13. Solomon restored the Aaronic line to the high-priesthood; he replaced Abiathar, Eli's descendant, with Zadok, from the line of Eleazar, I Kings 2:26,27,35. During the ministry of the prophet Jeremiah, Seraiah was the high-priest; he was taken prisoner and executed by Nebuzar-adan, II Kings 25:18-21. Seraiah's son, Josedech, was not allowed to function as high-priest. Instead, he lived and died as a prisoner in Babylon, Haggai 1:1,14. Josedech's son, Joshua, functioned as the high-priest during the ministry of Zechariah, Zech. 3:1.
The high-priests that followed Joshua were: Joiakim, Eliashib, Joiada, Johanan and Jaddua, who was the high-priest in the epoch of Alexander the Great. Tradition holds that Jaddua met the advancing armies of Alexander with the scroll of the book of Daniel, whereupon he read Alexander those passages in Daniel referring to Alexander. Alexander was impressed and, tradition maintains, favorably disposed toward the Jews from then on.
Jaddua's successors were: Onias I, Simon the Just; Onias II/Eleazar, and Alcimus. The latter two, Onias II and Alcimus, were notorious for their malfunction; indeed, Onias II was also known as Menelaus.
Then, according to I Chronicles 9:10; 24:7; Nehemiah 11:10, the high-priestly line passed over to the Asmonaean family, the course of Joiarib. It stayed in the Asmonean family until Herod the Great decimated the Asmoneaen family, and his brother-in-law, Herod, executed the final Asmonean high-priest, Aristobulus, in 35 BC.