In the Romanian popular tradition, they say each of us has a brother tree. It may be either a tree planted in our own garden, in a park or in a forest. In the worst case, we can choose a tree to look after. These trees can have different significances: the apple symbolizes rivalries, the chestnut tree signifies the fear of the unknown, the lilac is a symbol of genuine love, and the fir tree is a symbol of fighting with sufferings. Also, the hazelnut tree is a symbol of honesty, the olive tree a symbol of reconciliation; the peach tree is a symbol of obstacles that can be overcome; the pear tree signifies cooperation; the cherry tree is an urge to take up initiatives.
Of course, the most celebrated tree is the Tree of Life. There are many theories about this tree, including the Kabalistic version on the matter. For the Christian part, represented for instance by St. Ambrose, the Tree of Life foreshadows our Lord and Savior Jesus Christ. Another saint from Jerusalem considered that there was a connection, a contrast between the tree of rebellion which was the beginning of sin and the tree of the Cross, which put an end to sin.
So, the tree of knowledge of good and evil is charged with symbolism again. Thus, St. Clement states that even the Holy Scripture denotes the sexual intercourse as a form of gaining knowledge, of getting to know. St. Clement says that this is a secondary type of knowledge represented by the tree of knowledge of good and evil. The Tree of Life represents yet another type of knowledge, that of Truth Itself. But, Saint Clement also gives a Christological interpretation to the Tree of Life. Thus, he says that heaven is the created world in which Logos has grown (as a tree of life) and born fruit by becoming man, and based people's lives on His Cross.
Origen supports the idea that the tree of Eden must not be interpreted word for word. He thus returns to the primary concept that of giving the Tree of Life the interpretation of a symbol of the Cross, but combines it with the reference to the double nature of the tree which not only the Good (Christ), but also the evil (the powers of this world) has been crucified, as Saint Paul the Apostle says in Colossians 2: 14-15. By this interpretation, the Tree of Life is identified with the tree of knowledge of good and evil.
This above-mentioned interpretation has played an important part for Gregory of Nyssa, who developed and refined it. For St. Gregory, heaven is a place of virtues, but the interpretation of the two trees as being virtually one and the same is his most important contribution in this context. He brings forth very complex arguments, in relation with the Song of songs 5-5, the myrrh being understood as a symbol of death and leads Gregory to demonstrate how the soul can rise from death through death. He says that in Eden, God's commandments were the law of life, announcing that man does not need to die, and the Tree of Life was in the middle of Eden. But, the death-bringing tree was also said to be there in the middle of Eden, although there couldn't possibly be place for two trees in the middle.
St. Gregory states that one and the same circle cannot have two centers. So, in the middle of God's garden was life, and death did not have any root or a place of its own to grow there. In other words, death does not have a substance of its own, it is only the absence of life. When we say that the tree of knowledge is at the same time of good and evil, this thing does not contradict this interpretation, because what is called good is what appears to be good from the point of view of desire, and what is called evil is what gives the opposite feeling. Sin is the correct name which can be given to the death-bringing fruits of this tree. Life is gained by taking part at life, and death by renouncing life. But, while the one who is dead for virtues lives in evilness, the one who is dead towards evil comes to life through virtue.