There is one tree that is in both the first and last book of the Bible. What is that tree?
In the first book of the Bible, Genesis, it talks about God creating the garden of Eden for Adam and Eve to dwell. In the midst of the garden, God put many trees -- and He also put the tree of life.
Adam and Eve sinned by eating from the tree of the knowledge of good and evil; they sinned by disobeying God. God then sent them out from the garden of Eden, lest Adam "stretch out his hand, and take also from the tree of life, and eat, and live forever." So the tree of life could give eternal life.
After the garden of Eden in Genesis Chapter 3, the tree of life is not found again until the very last book of the Bible -- the book of Revelation. In the very last chapter of Revelation, chapter 22, the Apostle John is describing heaven and eternal life.
John says, "And he showed me a river of the water of life, clear as crystal, coming from the throne of God and of the Lamb, in the middle of its street. And on either side of the river was the tree of life, bearing twelve kinds of fruit, yielding its fruit every month; and the leaves of the tree were for the healing of the nations."
So from Genesis to Revelation, God fulfills His loving plan of eternal life and healing! And the tree of life -- lost for generations -- will come back again in the end. God is faithful!