So I'm presently going back to The Elder Scrolls III: Morrowind on my Altmer Witchhunter character. Clearing out a Dunmer fortress, I came across the book entitled Sithis. Me being me, I decided to peek at the book to determine if it was anything this character would collect.

Well first off, the book surprised me because it isn't about Sithis - it's about Lorkhan. It also surprised me, because it seems like the unknown author is speaking directly to the Nerevarine.

This seems to be saying gather power and influence, and approach Dagoth Ur as an equal, that you might destroy him. That in and of itself is peculiar, but what struck me even more was the text afterward:

Lorkhan, Hermaeus Mora, and Padomay are easy enough to recognize - Bringer of Change, Hidden Knowledge, and the state of Change/Chaos. ALTADOON escaped me though, so I went to UESP and did some research.

ALTADOON appears in the Sermons - #23 to be exact - but I can't make heads or tails out of the meaning:

Altadoon is also the name of a temple that houses an Elder Scroll for the Aldmeri Dominion in The Elder Scrolls Online. I suppose the most likely answer is the book Sithis was written via revelations made by study of the Elder Scroll of Altadoon, but I was curious if others had some insight into the text.