Complete Works, Vol. V

generation original: "generationis": then the manner of the mixture of stones, and the cause of the diversity of their color and other accidents which are found in them, such as greater and lesser hardness, workability and unworkability, porosity and constriction, heaviness and lightness, and other things of this kind, in which stones are seen to have no small diversity, not only in species and number, but also in genus.

There are, however, certain men of greatest authority in philosophy who, making a treatise not on all, but on certain genera of stones, say that they have made sufficient mention of stones. Such are Hermes Cuates, King of the Arabs, Dioscorides, Aaron, and Joseph, who, treating only of precious stones, did not treat of the genus of stones. Pliny, however, in his Natural History original: "Historia naturali", handed down a less than sufficient understanding, not wisely assigning the causes of stones in general. Nor does it behoove us to adduce the opinion of all of these, because the science of a thing is not so occult that we must collect it from the errors of many. However, the natures and complexions the balanced combination of the four humors of stones are sufficiently known when their proper matter, and the proximate efficient the direct cause of their formation, and their form, and their proper accidents are known through the inquiry laid out in the fourth book of the Meteorology original: "Meteororum". For we do not intend here to show how one of these is transmuted into another, or how their illnesses are cured through the antidote of medicine which Alchemists call an elisir elixir, or how their occult properties are manifested, or conversely, how their manifest properties are detected: but rather to show their mixtures from the elements, and how each one is established in its own species. For this reason, we do not care to inquire into the difference between stone and spirit or soul, and body or substance and accident, about which the Alchimici Alchemists inquire, calling a "stone" everything that does not evaporate in fire, and calling the same a body and a substance. But that which evaporates in fire, such as

sulfur and quicksilver, and from which those things that are called stones are made of various colors, they call spirit and soul and accident: for it belongs to another science to inquire about those things which are supported by very occult reasons and instruments.

The method which we have held in individual cases, we shall also hold here, dividing the whole work into some books and several treatises and many chapters. Since, however, in many cases a treatise is made on particulars, it behooves us first to know the natures of these things from signs and effects, and from those to arrive at their causes and compositions: because signs and effects are more manifest to us. But in the nature of universals, of which we made mention in all the aforementioned books, it was necessary to proceed from the cause, namely, to the effects, to the virtues and signs: because in such things, common and confused things are more manifest to us, as was determined in the first book of the Physics original: "Physicorum".

Why the science of minerals should be ordered before the science of animate things. We have sufficiently shown the order of this book to the following books on nature at the end of our book Meteorology, where we said what must be said first and what later. Since, however, the genera of stones and metals are homogeneous homiomera uniform in composition more than plants, in which there is found a diversity of parts, which are root, leaf, flower, and fruit, and since homogeneous things are by nature before non-homogeneous things anhomiomera composed of different parts, therefore it will be necessary to treat of stones and other minerals before animate bodies.

CHAPTER II.

Beginning therefore to treat of the nature of stones, we say in general that the matter of every stone