In "Wolf Hall" by Hilary Mantel, a vivid concept is introduced, envisioning the idea that each book contains another book and every letter leads to an infinite expansion of knowledge. This imagery suggests that within every piece of written material, there lies an endless depth of information waiting to be discovered, yet it remains intangible and doesn't occupy physical space. The notion of knowledge being encapsulated in symbols or signs creates a fascinating picture of the relationship between learning and understanding.

Furthermore, Mantel outlines an intriguing metaphor about the human mind, comparing it to an ever-expanding vessel filled with knowledge. The idea of the skull as a space that opens and vibrates with ideas, akin to buzzing beehives, portrays the human capacity for thought and learning as limitless. This depiction emphasizes how the mind holds vast realms of information, akin to those hidden volumes within books, illustrating a profound connection between the universe of knowledge and the human experience.