In a fan-compiled document linked in a BZpower thread(1) that goes into cancelled and unused concepts for the Bionicle G1 story, it's briefly mentioned that Bob Thompson had forwarded an idea of there being seven 'books' of Bionicle prior to his departure, with the third being the Mask Of Life saga/Ignition trilogy. (Presumably that makes the Mata-Nui and Metru-Nui arcs the first and second.) Since this is the only source mentioning it that I can find, I wanted to verify if you remember this being discussed at all? And if so, was the planned content of the later 'books' brought up during those discussions?
(1) Citation: http://www.bzpower.com/board/topic/26473-early-unused-story-concepts-in-bionicle/