These two names of Mercury and of Sulfur are only names for one single substance which we know under the names of Quicksilver or Mercury...
Therefore make manifest that which is hidden and make occult that which is manifest. I tell you, in that alone consists the work of the sages. Our gum curdles our milk, and our milk dissolves our gum, and they grow in the Stone of Paradise, which Stone is of two contrary natures, that is to say, of the natures of Fire and of Water.
All that I have written above ought to have opened your understanding to the intelligence of the philosophers - for what I have explained to you altogether well and have given you to understand what our Sulphur is, that the philosophers have also called Gum, Oil, Sun, Fixity, Red Stone, Curd, Safran, Poppy, Red Brass, Tincture, Dry, Fire, Spirit, Agent, Soul, Blood, Burned Brass, Red Man, and Quick Earth. I have also given you a clear and concise explanation of that which the philosophers name Water, Milk, White Wrapper, White Manna, White Urine, Cold, Moisture which does not dampen, Body, Womb, Moon, White Woman, Changing Habit, volatile, patient, Virginal Milk, Lead, Glass, White Flower, Flower of Salt, Fleece, Veil, Venom, Alum, Vitriol, Air, Wind, Rainbow, Naked Woman, and so many other names which are only for the purpose of making us conceive the qualities, properties, and the two natures of male and female contained in our substance, which is nothing else but animated Quicksilver. It is this viscous moisture mixed with its earthy part, our Mercury, and the true foundation of all our science.
It is in this great number of terms that the wise men have taken pleasure in writing their sentiment relative to our science. All these names ought to convince you of the truth of our science, for all of them have only one meaning and all of them have for their purpose only to expose the hermaphroditic Mercury to us. It is feminine if it is considered as separated from the Sulfur which it contains within it and of which it is the substance; but it is masculine if it is considered according to its Sulfur with which it is united so intimately that it cannot be separated from it; and it can be said of their marriage that they are both of them in the same flesh.