Instruction on Priesthood, circa April 1835 [D&C 107]

11 Of necessity there are presidents, or presiding offices  growing out of, or appointed of, or from among those who are  ordained to the several offices in these two priesthoods. Of  the Melchizedek priesthood, three presiding high priests, cho sen by the body, appointed and ordained to that office, and up held by the confidence, faith and prayer of the church, form a  quorum of the presidency of the church. The twelve travel ling counsellors are called to be the twelve apostles, or special  witnesses of the name of Christ, in all the world: thus differ ing from other officers in the church in the duties of their call ing. And they form a quorum equal in authority and power  to the three presidents, previously mentioned. The seventy  are also called to preach the gospel, and to be especial witness es unto the Gentiles and in all the world. Thus differing from  other officers in the church in the duties of their calling: and  they form a quorum equal in authority to that of the twelve  especial witnesses or apostles, just named. And every descis ion made by either of these quorums, must be by the unanim ous voice of the same; that is, every member in each quorum  must be agreed to its decisions in order to make their decis ions of the same power or validity one with the other. -[A  majority may form a quorum when circumstances render it  impossible to be otherwise.]- Unless this is the case, their de cisions are not entitled to the same blessings which the decis ions of a quorum of three presidents were anciently, who were  ordained after the order of Melchizedek, and were righteous  and holy men. The decisions of these quorums, or either of  them are to be made in all righteousness; in holiness and low liness of heart; meekness and long suffering; and in faith and vir tue and knowledge; temperance, patience, godliness brotherly  kindness and charity, because the promise is, if these things  abound in them, they shall not be unfruitful in the knowl edge of the Lord. And in case that any decision, of these  quorums, is made in unrighteousness, it may be brought be fore a general assembly of the several quorums which consti tute the spiritual authorities of the church, otherwise there can  be no appeal from their decision.
12 The twelve are a travelling, presiding high council, to of ficiate in the name of the Lord, under the direction of the  presidency of the church, agreeably to the institution of heav en; to build up the church, and regulate all the affairs of the  same, in all nations: first unto the Gentiles, and secondly un to the Jews.
13 The seventy are to act in the name of the Lord, under  the direction of the twelve, or the travelling high council, in  building up the church and regulating all the affairs of the [p. 84]
Instruction on Priesthood, Kirtland, OH, ca. Apr. 1835; in Doctrine and Covenants, 1835 ed., pp. 82–89.