When a man has been called and ordained to the office of elder in the priesthood, he has the right to ordain priests and teachers. But it appears that laying on hands and pronouncing the prescribed words may not be enough to pass along priesthood power. Verse 2 shows us that, first, an elder must pray to make the ordination efficacious. Then verse 4 shows us how the power of the priesthood is passed along: “they ordained them by the power of the Holy Ghost, which was in them.”
The power of the Holy Ghost is the power by which ordinances and all things pertaining to the gospel of Jesus Christ are effected. It is how any of us can come to know truth (see Moroni 10:5). It is how we know that Jesus is the Christ. And in the next two chapters of the Book of Mormon we’ll be taught how each baptized member of the Church of Jesus Christ of Latter-day Saints can obtain and retain the gift of the Holy Ghost.