'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.

(References: Apocalypse Explained 507)

8. The second state is when a distinction is made between the things that are the Lord's and those that are man's own. Those which are the Lord's are called in the Word 'remnants', and here they are chiefly the cognitions of faith which a person has learned since he was a small child. These are stored away and do not come out into the open until he reaches this state. Nowadays this state rarely occurs without temptation, misfortune, and sorrow, which lead to the inactivity and so to speak the death of bodily and worldly concerns - the things which are man's own. In this way what belongs to the external man is segregated from what belongs to the internal. Within the internal are the remnants, stored away by the Lord until this time and for this purpose.