Doctrine and Covenants 104:1–10 (continued)

The second priesthood is called the priesthood of Aaron, because it was conferred upon Aaron and his seed, throughout all their generations. Why it is called the lesser priesthood is, because it is an appendage to the greater, or the Melchisedec priesthood, and has power in administering outward ordinances. The bishopric is the presidency of this priesthood, and holds the keys or authority of the same. No man has a legal right to this office, to hold the keys of this priesthood, except he be a literal descendant of Aaron. But as a high priest of the Melchisedec priesthood has authority to officiate in all the lesser offices, he may officiate in the office of bishop when no literal descendant of Aaron can be found, provided he is called and set apart and ordained unto this power by the hands of the Presidency of the Melchisedec priesthood.

The power and authority of the higher, or Melchisedec, priesthood, is to hold the keys of all the spiritual blessings of the church; to have the privilege of receiving the mysteries of the kingdom of heaven; to have the heavens opened unto them to commune with the general assembly and church of the First born; and to enjoy the communion and presence of God the Father and Jesus the Mediator of the new covenant.

The power and authority of the lesser, or Aaronic, priesthood is, to hold the keys of the ministering of angels, and to administer in outward ordinances—the letter of the gospel—the baptism of repentance for the remission of sins agreeably to the covenants and commandments.