What little we know of the life of William Shakespeare is at odds with what would be expected of the greatest humanitarian writer of the Renaissance. Is Shakespeare a pseudonym? The answer lies in Shakespeare's Sonnets and its baffling Dedication which is shown to be a code based on the ancient Polybius Square. The Dedication encodes the name of the scholar, politician and ambassador Sir Henry Neville who also encoded his diplomatic dispatches using the Polybian system. Astoundingly, this decryption is validated by an extensive pattern of cross-referencing to the sonnets themselves. Each encrypted word within the Dedication has an exact and predictable mapping to a numbered sonnet. This book not only overturns our understanding of the Sonnets - it demonstrates with mathematical precision that Sir Henry Neville is the true author of the works attributed to William Shakespeare. This is the proof.