A Treatise of Mercury and the Philosophers Stone

"A Treatise of Mercury and the Philosophers Stone" is one of the most important alchemic text by George Ripley where the author explains the practice of the Alchemy and its secrets.
From the text: "I will, my dearest Son, instruct thee in this Blessed Science, Which was hid from the Wise of old, to whom God was pleased to shew so much favour. Know therefore, that our Matter is the chiefest of all things in the Earth, and of least estimation and account, as will hereafter more plainly appear..."