936. The leaves of the tree were for the healing of the nations. This symbolizes the resulting rational truths by which people caught up in evils and the accompanying falsities are brought to think sanely and to live decently.
The leaves of the tree symbolize rational truths, as will be seen below. Nations symbolize people governed by goods and the accompanying truths, and in an opposite sense people caught up in evils and the accompanying falsities (no. 483). Here they symbolize people caught up in evils and the accompanying falsities, because we are told that the leaves were for healing them, and people caught up in evils and the accompanying falsities cannot be healed by the Word, because they do not read it. However, if they have the judgment, they can be healed by rational truths.
The same symbolic meanings found in this verse are found in the following verses in Ezekiel:
Behold, there was water, flowing from under the threshold of the temple (which turned into a river), along (whose) bank... were very many trees (good for food) on one side and the other..., (whose) leaves do not fall, and whose fruit is not consumed. They bear fruit again every month..., (on which account) their fruit is good for food, and their leaves for healing. (Ezekiel 47:1, 7, 12)
The subject there is also a new church.
Leaves symbolize rational truths because a tree symbolizes a person (nos. 89, 400), and every part of the tree - its branches, leaves, flowers, fruits, and seeds - then symbolizes accordant elements in the person. The branches symbolizes a person's sensory and natural truths, the leaves his rational truths, the flowers the first spiritual truths in his rational mind, the fruits the goods of love and charity, and seeds the final elements in the person and also the first.
 That leaves symbolize rational truths is clearly apparent from things seen in the spiritual world. For trees are also seen there, with leaves and fruits. Gardens and parks are found there that consist of trees. In the case of people possessing goods of love and at the same time truths of wisdom, fruit trees are seen with an abundance of beautiful leaves. But in the case of people who possess the truths of some wisdom, and who speak in accordance with reason, but lack goods of love, the trees appear full of leaves, but without any fruits. And in the case of people without any goods or truths of wisdom, the only trees seen are bare of any leaves, like trees in winter in the world. An irrational person is just such a tree.
 Rational truths are truths which most readily welcome spiritual truths, for a person's rational mind is the first receptacle of spiritual truths. Indeed, seated in a person's rational mind is his perception of truth in a form that the person does not himself see by deliberation, as he does the ideas that reside beneath his rational mind in a lower level of thought that is connected with his outer sight.
Leaves also symbolize rational truths in Genesis 3:7; 8:11; Isaiah 34:4; Jeremiah 8:13; 17:8; Ezekiel 47:12; Daniel 4:12, 14; Psalm 1:3; Leviticus 26:36; Matthew 21:19, 24:32; Mark 13:28. However, their symbolic meanings vary according to the kinds of trees. The leaves of the olive tree and grape vine symbolize rational truths seen as a result of celestial and spiritual light; the leaves of the fig tree symbolize rational truths seen as a result of a natural sight, and the leaves of the fir tree, poplar, oak, and pine symbolize rational truths seen a a result of a sensual sight. The leaves of the latter strike terror in the spiritual world when blown to and fro by a strong wind. These are the leaves meant in Leviticus 26:36 and Job 13:25. However, not so the leaves of the former.