Many a book is like a key to unknown chambers within the castle of one’s own self.

The line uses an architectural metaphor—"unknown chambers" in the "castle" of the self—to describe reading as a form of inward discovery rather than mere information-gathering. A book becomes a "key": it does not supply a ready-made identity, but unlocks latent rooms of feeling, memory, fear, or desire that the reader did not know were there. The image also implies that the self is vast, compartmentalized, and partly inaccessible without external prompts. In a broadly Kafkaesque register, the castle suggests both grandeur and estrangement: the inner life can be intimidating and difficult to navigate, and literature can open doors that are illuminating but also unsettling.