St. Irenaeus on the Tree of Knowledge and the Cross

Top: Christ descends into Hell to bring His salvation to the righteous.
Bottom: Adam & Eve eat of the forbidden fruit; and Paradise is lost.

"The sin that was wrought through the tree was undone by the obedience of the tree, obedience to God whereby the Son of man was nailed to the tree, destroying the knowledge of evil, and bringing in and conferring the knowledge of good; and evil is disobedience to God, as obedience to God is good. And therefore the Word says through Isaiah the prophet, foretelling what was to come to pass in the future—for it was because they told the future that they were "prophets"—the Word says through him as follows: I refuse not, and do not gainsay, my back have I delivered to blows and my cheeks to buffets, and I have not turned away my face from the contumely of them that spat. [Is. 50, 6]

So by obedience, whereby He obeyed unto death, hanging on the tree, He undid the old disobedience wrought in the tree. And because He is Himself the Word of God Almighty, who in His invisible form pervades us universally in the whole world, and encompasses both its length and breadth and height and depth—for by God's Word everything is disposed and administered—the Son of God was also crucified in these, imprinted in the form of a cross on the universe; for He had necessarily, in becoming visible, to bring to light the universality of His cross, in order to show openly through His visible form that activity of His: that it is He who makes bright the height, that is, what is in heaven, and holds the deep, which is in the bowels of the earth, and stretches forth and extends the length from East to West, navigating also the Northern parts and the breadth of the South; calling in all the dispersed from all sides to the knowledge of the Father."

From a Meditation on the Tree of Knowledge and the Cross by Saint Irenaeus.