John Heydon (1629 - 1667 or 1670) was an English Rosicrucian, alchemist, and attorney. He published more than ten books during the last twelve years of his life. In this work is a chapter called "Chemical Dictionary," which contains a useful set of definitions of various terms used in Alchemy. That chapter includes much excellent advice for students of Alchemy, such as, "Try not at first experiments of great cost, or great difficulty, for it will be a great discouragement to thee, and thou will be very apt to mistake." There is an interesting section on sounds and harmonies: "We have also Sound-houses, where we practise and demonstrate all sounds, and their Generation." (near pg. 55). The figure near the end of Part I incorporates the image of a serpent (dragon) eating its own tail: Ouroboros. This image is included in various forms in other Alchemical works, including "The Golden Chain of Homer" and "Lamspring's Process," both available in The R.A.M.S. Library of Alchemy (Volumes 33 and 28). The illustrations were not included in the original R.A.M.S. edition. They were added from the 1662 printed edition. This 2nd edition includes Part I and Part II of the original text.