Two fragments re what I wrote briefly below on things that cannot be imagined. The first from Vlatka:

"i remember coming across some guy's site - an ongoing list/catalogue he was keeping - along the lines of 'things the internet couldnt find today'. i think it started with a few things he was googling and the search came with 'sorry. no results' - type thing. and then he started trying to come up with things to type into search engines which it would produce no hits for. i dont know why this came to mind - clearly such a different universe from your 'cannot be imagined' things... but the fact that the internet cant come up with it at all, anywhere, must mean that it's somehow not imaginable...

I was also thinking about the relation of what can be imagined to what can be said - is that the same thing necessarily? as in: if you can say it, does that automatically make it imaginable... in the sense that words alone conjure it up, make it happen. or is the 'cannot be imagined' more like something that cant even be put into words... - thus your empty notebook..."

 The second from my friend A.:

Liked a lot your thoughts of the person with the two identical notebooks - especially as I am working on a book/dvd-project titled un_imaginable... I like the clarity of this from a text by Jill Bennet:

"The unimaginable materializes as a condition of shock, trauma or surprise in the face of an event that is unforeseen, hitherto unimagined. As Jacques Ranciere observes, the discourse of the unimaginable is only ever 'authorized' by the event's having happened. Paradoxically, it is named as such only once its occurrence renders it imaginable.  ....There is no recapturing a state of unimaginability; the event, once it has occurred, becomes impossible to reimagine in the terms that rendered it unimaginable.  At no point, then - before or after the fact - is unimaginability concretely knowable and representable..."