Why are there blank pages in sirian's book he gave to the humans in micromegas

Life is complex and as such, should be completed with its own set of complexity. no book will ever describe humans. humans must write the pages their selves in their heads

Ifound this on google “what are motifs? a motif is a literary term that is an idea, object, or concept that repeats itself throughout a text. a motif gives clues to theme or reinforces ideas an author wants to emphasize.” i hope this for what your looking for