opening of the book introduces the concept of alchemy, emphasizing its dual nature as both a physical practice and a spiritual philosophy. Redgrove explains that while alchemy is often simplistically viewed as the quest to transform base metals into gold through the Philosopher's Stone, it actually represents a deeper investigation into the nature of reality. He highlights the alchemists' belief in a cosmic unity and their attempts to realize this through experimental methods, while also recognizing the significant mystical elements within their doctrines. The opening sets the stage for the subsequent exploration of the lives and teachings of notable alchemists and their contributions to chemistry and mysticism. (This is an automatically generated summary.)