Excerpt from the Letter of Clement, ca. 96
Chapter XL.-Let Us Preserve in the Church the Order Appointed by God.
These things therefore being manifest to us, and since we look into the depths of the divine knowledge, it behoves us to do all things in [their proper] order, which the Lord has commanded us to perform at stated times. He has enjoined offerings [to be presented] and service to be performed [to Him], and that not thoughtlessly or irregularly, but at the appointed times and hours. Where and by whom He desires these things to be done, He Himself has fixed by His own supreme will, in order that all things being piously done according to His good pleasure, may be acceptable unto Him. Those, therefore, who present their offerings at the appointed times, are accepted and blessed; for inasmuch as they follow the laws of the Lord, they sin not. For his own peculiar services are assigned to the high priest, and their own proper place is prescribed to the priests, and their own special ministrations devolve on the Levites. The layman is bound by the laws that pertain to laymen.
Chapter XLI.-Continuation of the Same Subject.
Let every one of you, brethren, give thanks to God in his own order, living in all good conscience, with becoming gravity, and not going beyond the rule of the ministry prescribed to him. Not in every place, brethren, are the daily sacrifices offered, or the peace-offerings, or the sin-offerings and the trespass-offerings, but in Jerusalem only. And even there they are not offered in any place, but only at the altar before the temple, that which is offered being first carefully examined by the high priest and the ministers already mentioned. Those, therefore, who do anything beyond that which is agreeable to His will, are punished with death. Ye see, brethren, that the greater the knowledge that has been vouchsafed to us, the greater also is the danger to which we are exposed.
Chapter XLII.-The Order of Ministers in the Church.
The apostles have preached the Gospel to us from the Lord Jesus Christ; Jesus Christ [has done sol from God. Christ therefore was sent forth by God, and the apostles by Christ. Both these appointments, then, were made in an orderly way, according to the will of God. Having therefore received their orders, and being fully assured by the resurrection of our Lord Jesus Christ, and established in the word of God, with full assurance of the Holy Ghost, they went forth proclaiming that the kingdom of God was at hand. And thus preaching through countries and cities, they appointed the first-fruits [of their labours], having first proved them by the Spirit, to be bishops and deacons of those who should afterwards believe. Nor was this any new thing, since indeed many ages before it was written concerning bishops and deacons. For thus saith the Scripture in a certain place, "I will appoint their bishops in righteousness, and their deacons in faith."