Man has ever been overawed by the majesty of the stars; yet he has not failed to notice that the movements of these bodies are apparently capricious. The moon has always been to him a type of mutability; only in the sun has he seemed to find a settled resting-point. Now, when we remember that in the alchemical scheme of things the material earth and material heavens, the intellectual, the moral, and the spiritual world were regarded as one great whole, the parts of which were continuously acting and reacting on each other, we cannot wonder that the alchemist should regard special phenomena which he observed in his laboratory, or special forms of matter which he examined, as being more directly than other phenomena or other forms of matter, under the influence of the heavenly bodies. This connection became gradually more apparent to the student of alchemy, until at last it was fixed in the language and the symbols which he employed. Thus the sun (Sol) was represented by a circle, which likewise became the symbol for gold, as being the most perfect metal. The moon (Luna) was ever changing; she was represented by a half-circle, which also symbolized the pale metal silver. Copper and iron were regarded as belonging to the same class of metals as gold, but their less perfect nature was denoted by the sign + or ^. Tin and lead belonged to the lunar class, but like copper they were supposed to be imperfect metals. Mercury was at once solar and lunar in its properties. These suppositions were summed up in such alchemical symbols as are represented below-- [Illustration: Sol. Gold.] [Illustration: Luna. Silver.] [Illustration: Venus. Copper.] [Illustration: Mars. Iron.] [Illustration: Jupiter. Tin.] [Illustration: Saturn. Lead.] [Illustration: Mercury. Quicksilver.] Many of the alchemical names remain to the present time; thus in pharmacy the name "lunar caustic" is applied to silver nitrate, and the symptoms indicative of lead-poisoning are grouped together under the designation of "saturnine cholic." But as the times advanced the older and nobler conception of alchemy became degraded. If it be true, the later alchemists urged, that all things suffer change, but that a changeless essence or principle underlies all changing things, and that the presence of more or less of this essence confers on each form of matter its special properties, it follows that he who can possess himself of this principle will be able to transmute any metal into any other; he will be able to change any metal into gold.