Knowledge: "And out of the ground made the Lord God to grow every tree that is pleasant to the sight, and good for food; the tree of life also in the midst of the garden" Genesis 2:9. The fruit from the tree of life administered eternal life to the first couple in the Garden of Eden.
A Mystery: "Then Jesus said unto them, 'Verily, verily, I say unto you, except you eat the flesh of the Son of man, and drink his blood, you have no life in you'" John 6:53.
Wisdom: The cross upon which Jesus was hung and crucified is the tree of life for the fallen human race. Christ is "the way, and the truth, and the life" John 14:6 for those who will receive Him. Jesus is the fruit that hangs on the tree of life (the cross) for a sinful race of people, waiting for anyone to reach forth with a hand of faith and receive Him.