Moses 6

 

Moses was taught of Adam and his posterity - 

"Now this same Priesthood, which was in the beginning, shall be in the end of the world also."  Moses 6:7

The Prophet Joseph Smith taught - 

“The Priesthood was first given to Adam; he obtained the First Presidency, and held the keys of it from generation to generation. He obtained it in the Creation, before the world was formed…. The Priesthood is an everlasting principle, and existed with God from eternity, and will to eternity, without beginning of days or end of years. The keys have to be brought from heaven whenever the Gospel is sent. When they are revealed from heaven, it is by Adam’s authority” (Teachings of the Prophet Joseph Smith, page 157).

I find it informative that when priesthood keys are revealed "it is by Adam's authority"