A book in a dream often represents knowledge you're seeking or a story about yourself that's still being written. An unreadable or blank book can point to self-understanding that feels just out of reach, while finishing one may reflect a chapter of your life reaching genuine closure.
Always deliver judgements from the Stars in general terms, or if thou dost otherwise let it be when thou hast very evident testimonies and in great and weighty matters. - Cardan Girolamo (1501-1576)