To help us all, here is a typed version of that note:
"Through one of our mutual acquaintances, Marcy came to access what the men seem to be calling the All-Seeing Eye. Knowing it for what it was, she sent it on to me in her last correspondence, believing someone of my House would know what to ask.
When the Eye opened to me, it told me of the Hope for the fight in which our mundane brethren are embroiled. As for the second request, a far future was Illuminated. One where our Houses no longer have need to meet in secret between one another as we do now.
It is with those descendants in mind that we leave their messages. Each of our secret group has written a small note, twice-encoded to keep others in our respective houses from stopping us, addressed to our future counterparts. To my knowledge, none of them contain any Earth-shattering information about our houses, just a short greeting from each of us.
The Eye granted me the two cyphers used, and left with a clue to decrypt it.
The book will Guide you to play fair.
It means nothing to me, but it may to you.
Until your time comes, we shall continue to protect It, even from one another.
Faithfully Yours,
H.A.
As a more substantial gift from us, your predecessors, we have included some of our, shall we say, less mundane botanical artefacts. May they survive the years until this comes into your possession."
Soooo, if all of this is true, six people should be getting letters in the mail (looks like 5 for Bali and possibly Tinker for Flinterforge, which leaves Weatherwatch, Ebenguard, Thornmouth, and Gossmere up in the air). And apparently this H.A. fellow consulted with the Oracular Eye and asked for hope and illumination (just like we did, notably) and this happened a long time ago. During a mundane war but that’s… a bit tricky to narrow down. At any rate, I definitely agree with Sel that the clue leads us to the Guide.