This writing, which uses symbols of the heavenly form, is in use in the inmost heaven, whose inhabitants enjoy greater wisdom than others. It expresses the affections from which their thoughts flow and which follow in sequence according to the substance of the matter under consideration. This is why these writings enfold treasures that cannot be completely drawn out by thought. I have also been allowed to see these writings.
In the lower heavens, though, there are no written materials of this sort. The written materials there are much like those in our world, with similar letters. However, they are still not intelligible to people on earth because they are written in an angelic language, and angelic language by nature has nothing in common with our languages (Section 237). They express affections through the vowels; with the consonants they express the particular concepts that derive from the affections, and with the words they express the meaning of the matter (Sections 236, 241).
Further, this writing enfolds in a few words more than we can describe in several pages. I have seen these written materials as well. This means that they have a written Word in the lower heavens, and one expressed through heavenly forms in the inmost heaven.
from Heaven and Hell, Sections 261
Notes:
Section 236: Published 4/28/2021
Section 237: Published 4/29/2021
Section 241: Published 5/3/2021
Secrets of Heaven 