Joseph Smith - History

The priesthood seems to be a conduit of revelation for all upon whom it is conferred. Speaking of the Melchizedek priesthood, the Lord revealed -

"...this greater priesthood administereth the gospel and holdeth the key of the mysteries of the kingdom, even the key of the knowledge of God." (Doctrine and Covenants Section 84:19)

And also -

"The power and authority of the higher, or Melchizedek Priesthood, is to hold the keys of all the spiritual blessings of the church—
19 To have the privilege of receiving the mysteries of the kingdom of heaven, to have the heavens opened unto them..." (Doctrine and Covenants Section 107:18 - 19)

Even the lesser or the Aaronic priesthood -

"...holds the keys of the ministering of angels..." (Pearl of Great Price JS-History 1:69)

After having the Aaronic priesthood conferred upon Joseph Smith and Oliver by the hand of John the Baptist, and having baptized each other, the Prophet reports -

"Immediately on our coming up out of the water after we had been baptized, we experienced great and glorious blessings from our Heavenly Father. No sooner had I baptized Oliver Cowdery, than the Holy Ghost fell upon him, and he stood up and prophesied many things which should shortly come to pass. And again, so soon as I had been baptized by him, I also had the spirit of prophecy, when, standing up, I prophesied concerning the rise of this Church, and many other things connected with the Church, and this generation of the children of men. We were filled with the Holy Ghost, and rejoiced in the God of our salvation." (Pearl of Great Price JS-History 1:73)

And after having received the priesthood the Prophet writes -

"Our minds being now enlightened, we began to have the scriptures laid open to our understandings, and the true meaning and intention of their more mysterious passages revealed unto us in a manner which we never could attain to previously, nor ever before had thought of." (Pearl of Great Price JS-History 1:74)

All in accordance to revealed knowledge.