'A sandal tree' signifies aspects of the natural self.

(References: Apocalypse Explained 518)

333. And we shall reign on the earth. That this signifies the power that belongs to the Lord alone by means of the Divine truth, united to the Divine good, and the power and wisdom thence to those who are of the Lord's spiritual and celestial kingdom, is clear from the signification of reigning, as denoting to be in truths and goods, and thence, from the Lord, to be in the power of resisting the evils and falsities that are from hell; and because truths and goods are from the Lord alone, and all power is in truths from good, therefore by reigning is signified the power that belongs to the Lord alone by means of the Divine truth united to the Divine good, and the power thence to those who are in the Lord's spiritual and celestial kingdom. He who does not rightly understand the Word in the spiritual sense, will suppose that they will be as kings and priests, and reign with the Lord; but, in the spiritual sense, by kings are meant truths, and by priests goods apart from persons, or in persons, from the Lord; hence it follows that truths from good shall reign, thus the Lord alone, from whom they are. The angels indeed possess great power; but still they have no power of themselves; indeed should one who is in heaven believe that he has power from himself, he is instantly deprived of it, and then he is altogether impotent. The reason it is said in the sense of the letter, that they shall reign, is, because the sense of the letter is personal; wherefore, when in that [sense] it is said, that they shall be kings and priests, it is also said that they shall reign; but in the spiritual sense everything associated with person is put off, and thence everything of dominion belonging to it, and it is left to the Lord alone.

Similar to this case is that in which the Lord said to His disciples, that they should sit upon twelve thrones, and judge the twelve tribes of Israel (Matthew 19:28; Luke 22:30). Then what the Lord said to Peter, That to him belonged the keys of the kingdom of the heavens (Matthew 16:19). By this is not meant that the disciples and Peter should have that power, but the Lord alone; because, in the spiritual sense, by the twelve disciples are meant all the truths and goods of the church from the Lord; and by Peter is meant truth from good from the Lord. (That by the disciples are meant all the truths and goods of the church from the Lord, may be seen above, n. 100, 122. That Peter signifies truth from good from the Lord, may be seen in the small work concerning the Last Judgment 57; and above, n. 9, 206, 209. That all power belongs to truth from good from the Lord, thus to the Lord alone, and that thence the angels have power, may be seen in the work concerning Heaven and Hell 228-233.) That by, we shall reign, is also signified that they have wisdom from the Lord, is, because by kings and priests are signified truths and goods, and all wisdom is from truths that are from good from the Lord. It is said that they shall reign upon the earth, because by the earth is meant the Lord's church in the heavens and in the earths (see above, n. 304). That the earth also here does not signify the earth, is evident; thus neither that we shall be kings and priests. The reason why to reign signifies to be in truths from good, and thence in power and wisdom from the Lord, is, because a kingdom signifies heaven and the church as to truths, and a king truth from good. (That kingdom in the Word signifies heaven and the church as to truths, may be seen above, n. 48; and a king, truth from good, also above, n. 31. The same is signified by reigning in the following passages, 20:4, 6; 22:4.)