This is the first book to explore the importance of alchemy and its links to the occult in the period between 1320 and 1400. Alchemists did more than try to transmute base metals into gold: they studied planetary influences on metals and people, refined plants and minerals in the search for medicines and advocated the regeneration of matter and spirit. This book illustrates how this new branch of thought became increasingly popular as the practical and theoretical knowledge of alchemists spread throughout England. Adopted by those in court and the circles of nobility for their own physical and spiritual needs, it was adapted for the diagnosis and therapeutic treatment of the illnesses of the body politic and its head, the king. This is the first work to synthesize all aspects of alchemy and show its contribution to intellectual, social and political life in the fourteenth century. Hughes explores a rich body of manuscripts to reveal the daily routines of the alchemist and his imaginative mindscape, and considers the contribution of alchemy to the vernacular culture and political debate, leading to a reassessment of the intellectual life of the middle ages.