936. 'And the leaves of the tree are for the healing of the nations' signifies the rational truths therefrom by means of which those who are in evils and consequently in untruths are led to thinking soundly and living properly. By 'the leaves of the tree' are signified rational truths, treated of below. By 'the nations' are signified those who are in goods and consequently in truths, and in the opposite sense those who are in evils and consequently in untruths (n. 483). Here it is those who are in evils and consequently in untruths, because it is said 'for their healing', and those who are in evils and consequently in untruths cannot be healed by the Word, because they do not read it; but if they have a strong judgment they can be healed by means of rational truths. Things similar to those in this verse are signified by these words in Ezekiel:-
Behold waters going forth from under the threshold of the house from which there is a river, upon the banks of which is a tree of very much food on this side and that, whose leaf does not fall, nor is consumed; it is reborn month by month (in menses), whence its fruit is for food, and its leaf for medicine Ezek. xlvii 1, 7, 12;
where also the New Church is treated of. The reason why by 'the leaves' are signified rational truths is because by 'a tree' is signified a man (n. 89, 400); and then by all [the parts] of a tree are signified the things agreeing to them with the man, as by the branches, leaves, flowers, fruits and seeds. By 'the branches' are signified the man's natural and sensual truths, by 'the leaves' his rational truths, by 'the flowers' the earliest spiritual truths in the rational, by 'the fruits' the goods of love and charity, and by 'the seeds' are signified the man's last and first things.  That by 'the leaves' are signified rational truths appears clearly from the things seen in the spiritual world; for trees appear there also, with leaves and fruits. There are gardens and paradises composed of them there. With those who are in goods of love and at the same time in truths of wisdom there appear fruit trees with beautiful luxuriant foliage; but with those who are in truths of some wisdom and speak reasonably and are not in goods of love, there appear trees with plenty of leaves but without fruit. But with those who have neither goods nor truths of wisdom, trees only appear stripped of leaves like those in the world in the time of winter. A man not rational is nothing else but such a tree.  Rational truths are those that proximately receive spiritual truths, for a man's rational is the first receptacle of spiritual truths; for in the man's rational there is a perception of truth in some form, which the man himself does not see by a process of thought as he does those that are beneath the rational in 'the lower kind of thought that conjoins itself with external sight. Rational truths are signified by 'leaves' also (Gen. iii 7; viii 11; Isa. xxxiv 4; Jer. viii 13; xvii 8; Ezek. xlvii 12; Dan. iv 12, 14 [H.B. 9, 11]; Ps. i 3; Lev. xxvi 36; Matt. Xxi 19; xxiv 32; Mark xiii 28); but [the leaves] are significant according to the species of the trees. The leaves of the olive and the vine signify truths rational by virtue of celestial and spiritual light, the leaves of the fig-tree truths rational by virtue of natural light, while the leaves of the fir, poplar, oak and pine signify truths rational by virtue of sensual light. The leaves of these excite terror in the spiritual world when they are shaken by a strong wind. These are the ones understood in Lev. xxvi 36; Job xiii 25. But with the leaves of the former [species] it is not so.