Basil Valentine's Last Will and Testament contains countless explanations and clarifications of his earlier writings. From the preface, "[This is] the most principal, excellent, and plain of all his works; and I may justly say, of all the Books that are extant on this subject." Of particular interest are his explanations of The Twelve Keys of Basil Valentine, which has long perplexed researchers into the art of Alchemy. In this section, Basil says, "The things I do write of, I know experimentally to be true." The text contains details of his actual experiments, both successes and failures, including the preparation of the Stone of the Philosophers. There is a step by step explanation of the process for the preparation of the Aurum Potable, in which Basil writes in Part 5, "My intention is to make a perfect relation of aurum potable, for the benefit of good and understanding men." Another type of aurum potable is also presented, and a half-aurum potable, with two methods for its preparation, plus the preparation of potable silver. The Manuals, or manual operations, are extensively described after Book 5. One example is the preparation of the sweet Essence of Vitriol, and some of its uses are described: "This Essence of Sulphur, four grains of it being taken in Balm-water, dries up the bad humors of the blood, strengthens and incites Men and Women to Copulation, cleans the womb, hinders the Rising of the Mother, and breeds good Seed for the Procreation of Children." The Last Will and Testament is an amazingly clear work on Alchemy, and I recommend it highly.