“Geber clearly shews that the substance of our Stone cannot exist in imperfect metals; because things that are impure in themselves do not abide the fire which might purify them, while our mercury (on account of its purity) is not in the slightest degree injured by the fire.” - Anonymous. The Golden Tract Concerning The Stone of the Philosophers
"Mercurius stands at the beginning and end of the work: he is the prima materia, the caput corvi, the nigredo; as dragon he devours himself and as dragon he dies, to rise again in the lapis." (Psychology and Alchemy, par. 528)
“Gold is by Art dissolved with Mercury, that the unripe may be holpen by the ripe, and so Art decocting, and Nature perfecting, the Composition is ripened by the favor of Christ.” - Bernard Trevisan The Answer of Bernardus Trevisanus, to the Epistle of Thomas of Bononia
“The seed of metals is what the Sons of Wisdom have called their mercury, to distinguish it from quicksilver, which it nearly resembles, being the radical moisture of metals. This, when judiciously extracted, without corrosives, or fluxing, contains in it a seminal quality whose perfect ripeness is only in gold; in the other metals it is crude, like fruits which are yet green, not being sufficiently digested by the heat of the sun and action of the elements.” - Collectanea Chemica Collectanea Chemica
"When the alchemist speaks of Mercurius, on the face of it he means quicksilver (mercury), but inwardly he means the world-creating spirit concealed or imprisoned in matter. The dragon is probably the oldest pictoral symbol in alchemy of which we have documentary evidence. It appears as the Ouroboros, the tail-eater, in the Codex Marcianus, which dates from the tenth or eleventh century, together with the legend ‘the One, the All’. Time and again the alchemists reiterate that the opus proceeds from the one and leads back to the one, that it is a sort of circle like a dragon biting its own tail. For this reason the opus was often called circulare (circular) or else rota (the wheel). Mercurius stands at the beginning and end of the work: he is the prima materia, the caput corvi, the nigredo; as dragon he devours himself and as dragon he dies, to rise again in the lapis. He is the play of colours in the cauda pavonis and the division into the four elements. He is the hermaphrodite that was in the beginning, that splits into the classical brother-sister duality and is reunited in the coniunctio, to appear once again at the end in the radiant form of the lumen novum, the stone. He is metallic yet liquid, matter yet spirit, cold yet fiery, poison and yet healing draught - a symbol uniting all the opposites." — Carl Jung, Psychology and Alchemy, Part 3, Chapter 3.1
"O great Mercury of the Philosophers! It is in you that Gold and Silver unite, after being brought from potentiality into act: Mercury all Sun and all Moon; triple Substance in one, and one Substance in three. O admirable thing! Mercury, Sulphur, and Salt show us three Substances in one single Substance." — "Light Emerging from Darkness by Itself", Bibliotheque des philosophes chimiques: tome troisiéme, c. 1741
Mercury is talking about himself: I am the poison-dripping dragon, who is everywhere and can be cheaply had. That upon which I rest, and that which rest upon me, will be found within me by those who pursue their investigations in accordance with the rules of the Art. My water and fire destroy and put together; from my body you may extract the green lion and the red. But if you do not have exact knowledge of me, you will destroy your five senses with my fire. By the philosophers I am named Mercurius. My spouse is the gold; I am the old dragon found everywhere on the globe of the earth, father and mother, young and old, very strong and very weak, death and resurrection, visible and invisible, hard and soft; I descend into the Earth and ascend into the Heavens, I am the highest and the lowest, the lightest and the heaviest. I am dark and light. Often the order of nature is reversed in me. I am known yet do not exist at all. I am the carbuncle of the sun, the most noble purified earth, through which you may change copper, iron, tin and lead into gold. A waxing poison comes from my nose, having brought to death many people. Therefore, with the art, you have to separate the course from the fine, if you don’t wan to delight in poverty. I give you the power of the male and the female, even that of heaven and earth. With bravery and broadness of understanding, the mysteries of my art are to be done, if you want to conquer me with the power of the fire. From which many have suffered in their potential and work. I am the egg of nature, that only the wise man knows, who by piety and modesty let the microcosm arise out of me, what is destined to people by the most high God, but what is given only to a few, while most long for it in vain: that they do well to those in poverty from my treasury and that their soul will not cling to the transitory gold. I am called Mercurius by the Philosphers; my mate is the philosophical gold; I am the old dragon, present everywhere on earth, father and mother, young man and old man, very powerful and very weak, death and rebirth, hard and soft; I descend into the earth and ascend into heaven’ I am the highest and the lowest, the heaviest and the lightest; often the order of nature in color, number , weight and measure is being reversed in me, I contain the light of nature (lumen naturale); I am the dark and the light, I come forth from heaven and earth; I am known but do not exist; all colors radiate in me and all metals by the sun’s rays. I am the solar carbuncle, the most refined, glorified earth, by which you can change copper, iron, tin and lead into gold.
- The Theatrum Chemicum, c. 1613