"Think most diligently about this; often bear in mind, observe and comprehend, that all minerals and metals together, in the same time, and after the same fashion, and of one and the same principal matter, are produced and generated. That matter is no other than a mere vapour, which is extracted from the elementary earth by the superior stars, or by a sidereal distillation of the macrocosm; which sidereal hot infusion, with an airy sulphurous property, descending upon inferiors, so acts and operates as that there is implanted, spiritually and invisibly, a certain power and virtue in those metals and minerals; which fume, moreover, resolves in the earth into a certain water, wherefrom all metals are thenceforth generated and ripened to their perfection, and thence proceeds this or that metal or mineral, according as one of the three principles acquires dominion, and they have much or little of sulphur and salt, or an unequal mixture of these; whence some metals are fixed--that is, constant or stable; and some are volatile and easily changeable, as is seen in gold, silver, copper, iron, tin, and lead." (Basil Valentine.) "To grasp the invisible elements, to attract them by their material correspondences, to control, purify, and transform them by the living power of the Spirit--this is true Alchemy." (Paracelsus.) "Destruction perfects that which is good; for the good cannot appear on account of that which conceals it.... Each one of the visible metals is a concealment of the other six metals." (Paracelsus.) These sayings read like sentences in a forgotten tongue. Humboldt tells of a parrot which had lived with a tribe of American Indians, and learnt scraps of their language; the tribe totally disappeared; the parrot alone remained, and babbled words in the language which no living human being could understand. Are the words I have quoted unintelligible, like the parrot's prating? Perhaps the language may be reconstructed; perhaps it may be found to embody something worth a hearing. Success is most likely to come by considering the growth of alchemy; by trying to find the ideas which were expressed in the strange tongue; by endeavouring to look at our surroundings as the alchemists looked at theirs. Do what we will, we always, more or less, construct our own universe. The history of science may be described as the history of the attempts, and the failures, of men "to see things as they are." "Nothing is harder," said the Latin poet Lucretius, "than to separate manifest facts from doubtful, what straightway the mind adds on of itself."