“I Give Unto You Power”
Nephi was not being given any additional priesthood by the Lord, but rather he was receiving new authority to perform ordinances associated with the “new organization” that Christ established among them. With “old things” done away, Nephi was given power and authority to administer in the “new things” in a dispensation with the fulness of gospel ordinances. Nephi, in turn, was then able to ordain (or in our terminology “set apart”) others to establish and set in order this new Church.
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