Paracelsus considered all the effects of plants as specifics, and the use of them as secrets. The same notions explain the eulogy which he bestowed on the _elixir of long life_, and upon all the means which he employed to prolong the term of existence. He believed that these methods, which contained the _materia prima_, served to repair the constant waste of that matter in the human body. He was acquainted, he says, with four of these arcana, to which he applied the mystic terms, _mercury of life_, _philosopher’s stone_, &c. The _polygonum persicaria_ was an infallible specific against all the effects of magic. The method of using it is, to apply it to the suffering part, and then to bury it in the earth. It draws out the malignant spirits like a magnet, and it is buried to prevent these malignant spirits from making their escape. The reformation of Paracelsus had the great advantage of representing _chemistry_ as an indispensable art in the preparation of medicines. The disgusting decoctions and useless syrups gave place to _tinctures_, _essences_, and _extracts_. Paracelsus says, expressly, that the true use of chemistry is to prepare medicines, and not to make gold. He takes that opportunity of declaiming against cooks and innkeepers, who drown medicines in soup, and thus destroy all their properties. He blames medical men for prescribing simples, or mixtures of simples, and affirms that the object should always be to extract the quintessence of each substance; and he describes at length the method of extracting this quintessence. But he was very little scrupulous about the substances from which this quintessence was to be extracted. The heart of a hare, the bones of a hare, the bone of the heart of a stag, mother-of-pearl, coral, and various other bodies may, he says, be used indiscriminately to furnish a quintessence capable of curing some of the most grievous diseases. Paracelsus combats with peculiar energy the method of cure employed by the disciples of Galen, directed solely against the predominating humours, and the elementary qualities. He blames them for attempting to correct the action of their medicines, by the addition of useless ingredients. Fire and chemistry, he affirmed, are the sole correctives. It was Paracelsus that first introduced _tin_ as a remedy for worms, though his mode of employing it was not good.