751. Therefore rejoice, ye heavens, and ye that dwell in them.- That this signifies the salvation and consequent joy of those who become spiritual by the reception of Divine Truth, is evident from the signification of rejoicing, as denoting joy on account of salvation; from the signification of the heavens, as denoting those who are spiritual (concerning which we shall speak presently); and from the signification of ye that dwell, as denoting those who live, here spiritually. That to dwell signifies to live, may be seen above (n. 133, 479, 662). The heavens signify those who are spiritual, because all who are in the heavens are spiritual, and because men who have become spiritual are also in the heavens, although they are in the world as to the body; therefore ye that dwell in the heavens means not only angels, but also men, for every man with whom the interior mind, which is called the spiritual mind, has been opened, is in the heavens, indeed, he also sometimes appears amongst the angels there. That this is so, has not been known in the world up to the present time. It must therefore be understood, that man as to his spirit is among spirits and angels, and indeed in that society of them into which he is to come after death. The reason of this is that the spiritual mind of man is formed exactly according to the image of heaven, and in such a way that it is a heaven in least form; consequently that mind, although still in the body, must nevertheless be where its form is. But this has been more fully dealt with in Heaven and Hell 51-58), where it is shown that every angel, and also every man as to his interiors, if he be spiritual, is a heaven in its least form, corresponding to heaven in its greatest form. For this reason where the Word treats of the creation of heaven and earth, the internal and external church is in general meant, and, in particular, the internal and external man, that is the spiritual and natural man. From these things it is evident that the heavens and those that dwell in them signify all who are there, and also those men who are becoming spiritual by the reception of Divine Truth in doctrine and life.

'Grass' is natural truth, and 'flower of the field' is spiritual truth, as in Isaiah 40:5, 6. Green grass, in the Word, signifies the good and truth of the church, and of faith, which first springs up in the natural man. This is also signified by 'herb in the field.' Grass and the pulse of the herb, as in Psalm 32:2, signify what is most vile. Grass signifies science from a spiritual origin, or that by which spiritual truth is confirmed. 'Reeds and rushes' signify science from a sensory origin, or the things which confirm the fallacies of the senses, as in Isaiah 25:7. This science, considered in itself, is only a part of the lowest natural degree, which may be justly called material and bodily, in which there is little or no life. Green grass also signifies that which is alive with man. 'Grass burnt up' signifies the things which are dead in him. Grass signifies the scientific principle. Just as green grass serves animals for support, spiritual truth serves men for spiritual nourishment.

(Referenties: Apocalypse Explained 507)