With all their mystery, their subterfuges, and their symbolism, the testimony of the alchemists themselves to the physical nature of their object is quite unequivocal and conclusive. One of the most celebrated experimental treatises in the English language is that entitled “The Marrow of Alchemy.” It professes to discover the secrets and most hidden mystery of the philosopher’s elixir, both in theory and practice. It was published by Eirenæus Philoponos Philalethes, that is George Starkey, and is generally supposed to be the work of the true Philalethes; at any rate it develops his principles, and derives its inspiration from the author of the _Introitus Apertus._ Now, this little book testifies over and over again, and that in the most emphatic manner, to the physical object of the alchemists, and to the fact that they operated on common gold. “The first matter which we take for our work is gold, and with it mercury, which we decoct till neither will forsake the other, in which work both die, rot by putrefaction, and after that are regenerate in glory. _It is actual gold and nothing else._ What does not equal a metal in weight will never enter it in flux. Nothing but the metalline will dwell with metals.” A severe criticism is passed on the blind folly of those who endeavour to reap the secret stone from strange material subjects. “Gold is the subject of our art alone, since by it we seek gold.” Those who, like the noble son of art, Morien, advise students to descend into themselves to find the true matter, only intended to point out how kind begets kind:-- “As then himself his likeness did beget, So gold must gold, this law’s to Nature set.” Morien adds that the secret stone must be sought in the dunghill, which signifies, says the “Marrow of Alchemy,” that the metal must be brought to putrefaction. “Those who assert that common gold is not the matter are in error. Gold is one. No other substance under Heaven can compare with it. Gold is the noble seed of our art. Yet it is dead. It needs to be unloosed, and must go to water. It must be tempered with its own humidity; it must be blent with our true water, disposed in a due vessel, closed with all caution, settled in a due nest, and with due fire inclined to motion.” It becomes the true gold of the philosophers when by a retrograde motion it tends to resolution. “Then it is our Sun, our Marchasite, and, joined with our Moon, it becomes our bright crystal Fountain.” * * * * *