Because the angels have speech, and their speech consists of words, they also have writings, and by writing as well as by speech they give expression to what is in their minds (animus). At times I have had sent to me papers, with writings made on them exactly like manuscripts and also like those printed in the world. I was able also to read them in the same manner, but was not allowed to draw from them more than one or two ideas, for the reason that it is not in accordance with Divine order for man to be taught by writings from heaven, but only by the Word, since by that alone there is communication and conjunction of heaven with the world, thus of the Lord with man. That papers written in heaven were seen also by the prophets is shown in Ezekiel:

When I looked, behold a hand was put forth by a spirit unto me, and a roll of a book was therein which he unrolled in my sight; it was written on the front and on the back. Ezek. ii. 9, 10.

And in John:

I saw upon the right hand of Him that sat on the throne a book written within and on the back, sealed up with seven seals. Rev. v. 1.