President Joseph F. Smith taught,

“The priesthood … is … the power of God delegated to man by which man can act in the earth for the salvation of the human family, in the name of the Father and the Son and the Holy Ghost, and act legitimately; not assuming that authority, nor borrowing it from generations that are dead and gone, but authority that has been given in this day in which we live by ministering angels and spirits from above, direct from the presence of Almighty God.”

Joseph F. Smith, Gospel Doctrine, 5th ed. (1939), 139–40; emphasis added.