Theodoret of Cyrus: Name of the Tree is Metonymic, Like the "Living Water" for Baptism

Should the tree of life and the tree of the knowledge of good and evil be taken as spiritual or material?

According to holy Scripture, they also sprouted from the ground, so they had a nature no different from that of other plants. Just as the tree of the cross was a tree and is called "saving" because salvation is accompanied by faith in it, so these trees were products of the soil. By divine decree the one was called the "tree of life," the other, since the perception of sin occurred in connection with it, "the tree of the knowledge of good and evil." Adam was set a trial with regard to the latter, whereas the tree of life was proposed as his prize for keeping the commandments. Similarly, the patriarchs bestowed names on places and wells. They called one "well of vision," not because it granted faculty of sight, but because the Lord of the universe was seen near it, and another "well of broad places," because the people of Gerar, who had often fought over the other wells, did not interfere with those digging this one. Likewise, there was a "well of the other" because the people used to swear oaths nearby. And the name "Bethel" or "House of God" was given to Luz, because that was where the Creator of the universe appeared to Jacob. There was a "hill of witness," not that the hill was alive, but because that was where they made treaties with one another. Likewise baptism is called "living water," not because the water of baptism has a different nature, but because, through that water, divine grace confers the gift of eternal life. Thus, the "tree of life" received its name from the divine decree and the "tree of knowledge" from the sense of sin gained in connection with it. To that point, they had no experience of sin, but afterwards, when they had partaken of the forbidden fruit, they suffered the pangs of conscience for breaking the commandment.

- Theodoret of Cyrus (around A.D. 393 to around A.D. 457), Questions on the Octateuch, Question 26 on Genesis, pp. 63-65 (2007), Robert C. Hill translator.