Revelation 5

As a door into heaven is opened, John witnesses one of the most grand events of our pre-mortal existence as he -

"...saw in the right hand of him that sat on the throne a book written within and on the backside, sealed with seven seals."  (New Testament | Revelation 5:1)

The Prophet Joseph Smith answered of the book -

"We are to understand that it contains the revealed will, mysteries, and the works of God; the hidden things of his economy concerning this earth during the seven thousand years of its continuance, or its temporal existence."  (Doctrine and Covenants | Section 77:6)

And that -

"...the first seal contains the things of the first thousand years, and the second also of the second thousand years, and so on until the seventh."  (Doctrine and Covenants | Section 77:7)

Obviously, this book was the plan of salvation for all of The Father's children as well as the mission of the Savior for John saw that -

"...a strong angel proclaiming with a loud voice, Who is worthy to open the book, and to loose the seals thereof?
3 And no man in heaven, nor in earth, neither under the earth, was able to open the book, neither to look thereon.
4 And I wept much, because no man was found worthy to open and to read the book, neither to look thereon."  (New Testament | Revelation 5:2 - 4)

What a touching experience for John.  The Father held in His hand a great plan of salvation for all His children, yet there appeared to be no one that was worthy (not even close) to open it, or in other words, make this plan possible.  And then one of the elders comforted John, saying -

"...Weep not: behold, the Lion of the tribe of Juda, the Root of David, hath prevailed to open the book, and to loose the seven seals thereof."  (New Testament | Revelation 5:5)

In other words, Jesus Christ was worthy (the only one worthy) to open and perform what was necessary to accomplish the Father's great plan of salvation.  And then seeing a vision within a vision, John saw that -

"...in the midst of the throne and of the four beasts, and in the midst of the elders, stood a Lamb as it had been slain..."  (New Testament | Revelation 5:6)

In this vision John saw and testified of that which was written in the book, that the Savior, the Lamb of God had been slain to atone for the sins and death of the world.  What a marvelous experience this must have been.  Seeing this also suggested that the Savior's atonement was already in force in our pre-mortal existence.   And then John saw that the Savior, the only one worthy to open the book -

"...came and took the book out of the right hand of him that sat upon the throne."  (New Testament | Revelation 5:7)

Being the right hand of Him on the throne would signify that the Savior then made a covenant with God to fulfill the atonement and priesthood leader that was necessary in the book.  Is there any wonder that -

"...the morning stars sang together, and all the sons of God shouted for joy?"  (Old Testament | Job 38:7)

John witnesses this as he saw and heard them sing  -

 "...a new song, saying, Thou art worthy to take the book, and to open the seals thereof: for thou wast slain, and hast redeemed us to God by thy blood out of every kindred, and tongue, and people, and nation;
10 And hast made us unto our God kings and priests: and we shall reign on the earth.
11 And I beheld, and I heard the voice of many angels round about the throne and the beasts and the elders: and the number of them was ten thousand times ten thousand, and thousands of thousands;
12 Saying with a loud voice, Worthy is the Lamb that was slain to receive power, and riches, and wisdom, and strength, and honour, and glory, and blessing."  (New Testament | Revelation 5:9 - 12)

Thus the Savior was "slain to receive power" sufficient that by His grace, that we can become kings and priests (which suggests kingdoms). Thus just as the elders did, we must have -

"...fell down and worshipped him that liveth for ever and ever."  (New Testament | Revelation 5:14)