The Aaronic priesthood failed God in two things: in ministering God's word and in exercising God's authority. This is why the New Testament charges the elders to learn to do two things: to teach the saints (1 Tim. 3:2; 5:17), that is, to speak the word of God; and to take the lead among the saints (Heb. 13:7; 1 Pet. 5:1-3), that is, to exercise God's authority. If the elders teach the saints, they must take the lead to practice whatever they teach. This is to exercise God's authority by taking the lead.
When the priesthood was proper, the priests were patterns to the people. What the priests taught and what they exercised in the authority of God, they themselves did, taking the lead to carry out all the things regarding God's eternal economy. For example, the priests took the lead to step into the river Jordan and then to circle the city of Jericho. That was the proper way to exercise God's authority. Today, this is the proper way to take care of the church—teaching to speak for God and taking the lead to exercise God's authority.
At the waning of the God-ordained priesthood, God began a new age in raising up Samuel, a young Nazarite, as a faithful priest to replace the waned priesthood (1 Sam. 2:35). God ministered His word to His elect by establishing Samuel as a prophet in the uplifted prophethood (3:20-21), and He exercised His authority over His elect by raising up Samuel as a judge (7:15-17).
Samuel, as the last judge, terminated the judgeship, and, as the new priest, brought in the kingship with the strengthening of the uplifted prophethood, in which Samuel was established as the first prophet (Acts 3:24; 13:20; Heb. 11:32). This means that God had put aside the old priesthood due to its deterioration. The old priesthood had the word of God and exercised the ruling of God. God replaced it with the uplifted prophethood to speak God's word to His people and the kingship to rule over God's people.
Such a condition was built up among God's people through Samuel. He set up a kind of governmental administration in God's economy that God could fulfill His promises to all the foregoing fathers and accomplish His desire according to His economy—that is, to have a lineage of genealogy to bring Christ to earth. Surely, the bringing forth of Christ was the greatest thing. Today we are participating in the benefit from Samuel's service. Thank God for this.