"The Voice of Knowledge" is a book by Don Miguel Ruiz, part of his Four Agreements series. It explores the concept of personal beliefs and how they shape our perception of reality. The book emphasizes the importance of questioning these beliefs to achieve personal freedom and inner peace. Ruiz discusses the idea that many of our thoughts are influenced by societal conditioning, leading to self-doubt and fear. By recognizing and transforming these limiting beliefs, individuals can reconnect with their true selves and live authentically. The book encourages readers to embrace their inner voice and trust their intuition.