As an indication of his grasp of some of the wider aspects of geological phenomena we reproduce, in Appendix A, a passage from De Ortu et Causis, which we believe to be the first adequate declaration of the part played by erosion in mountain sculpture. But of all of Agricola's theoretical views those are of the greatest interest which relate to the origin of ore deposits, for in these matters he had the greatest opportunities of observation and the most experience. We have on page 108 reproduced and discussed his theory at considerable length, but we may repeat here, that in his propositions as to the circulation of ground waters, that ore channels are a subsequent creation to the contained rocks, and that they were filled by deposition from circulating solutions, he enunciated the foundations of our modern theory, and in so doing took a step in advance greater than that of any single subsequent authority. In his contention that ore channels were created by erosion of subterranean waters he was wrong, except for special cases, and it was not until two centuries later that a further step in advance was taken by the recognition by Van Oppel of the part played by fissuring in these phenomena. Nor was it until about the same time that the filling of ore channels in the main by deposition from solutions was generally accepted. While Werner, two hundred and fifty years after Agricola, is generally revered as the inspirer of the modern theory by those whose reading has taken them no farther back, we have no hesitation in asserting that of the propositions of each author, Agricola's were very much more nearly in accord with modern views. Moreover, the main result of the new ideas brought forward by Werner was to stop the march of progress for half a century, instead of speeding it forward as did those of Agricola.

In mineralogy Agricola made the first attempt at systematic treatment of the subject. His system could not be otherwise than wrongly based, as he could scarcely see forward two or three centuries to the atomic theory and our vast fund of chemical knowledge. However, based as it is upon such properties as solubility and homogeneity, and upon external characteristics such as colour, hardness, &c., it makes a most creditable advance upon Theophrastus, Dioscorides, and Albertus Magnus—his only predecessors. He is the first to assert that bismuth and antimony are true primary metals; and to some sixty actual mineral species described previous to his time he added some twenty more, and laments that there are scores unnamed.

As to Agricola's contribution to the sciences of mining and metallurgy, De Re Metallica speaks for itself. While he describes, for the first time, scores of methods and processes, no one would contend that they were discoveries or inventions of his own. They represent the accumulation of generations of experience and knowledge; but by him they were, for the first time, to receive detailed and intelligent exposition. Until Schlüter's work nearly two centuries later, it was not excelled. There is no measure by which we may gauge the value of such a work to the men who followed in this profession during centuries, nor the benefits enjoyed by humanity through them.

That Agricola occupied a very considerable place in the great awakening of learning will be disputed by none except by those who place the development of science in rank far below religion, politics, literature, and art. Of wider importance than the details of his achievements in the mere confines of the particular science to which he applied himself, is the fact that he was the first to found any of the natural sciences upon research and observation, as opposed to previous fruitless speculation. The wider interest of the members of the medical profession in the development of their science than that of geologists in theirs, has led to the aggrandizement of Paracelsus, a contemporary of Agricola, as the first in deductive science. Yet no comparative study of the unparalleled egotistical ravings of this half-genius, half-alchemist, with the modest sober logic and real research and observation of Agricola, can leave a moment's doubt as to the incomparably greater position which should be attributed to the latter as the pioneer in building the foundation of science by deduction from observed phenomena. Science is the base upon which is reared the civilization of to-day, and while we give daily credit to all those who toil in the superstructure, let none forget those men who laid its first foundation stones. One of the greatest of these was Georgius Agricola.

DE RE METALLICA

Agricola seems to have been engaged in the preparation of De Re Metallica for a period of over twenty years, for we first hear of the book in a letter from Petrus Plateanus, a schoolmaster at Joachimsthal, to the great humanist, Erasmus,[16] in September, 1529. He says: "The scientific world will be still more indebted to Agricola when he brings to light the books De Re Metallica and other matters which he has on hand." In the dedication of De Mensuris et Ponderibus (in 1533) Agricola states that he means to publish twelve books De Re Metallica, if he lives. That the appearance of this work was eagerly anticipated is evidenced by a letter from George Fabricius to Valentine Hertel:[17] "With great excitement the books De Re Metallica are being awaited. If he treats the material at hand with his usual zeal, he will win for himself glory such as no one in any of the fields of literature has attained for the last thousand years." According to the dedication of De Veteribus et Novis Metallis, Agricola in 1546 already looked forward to its early publication. The work was apparently finished in 1550, for the dedication to the Dukes Maurice and August of Saxony is dated in December of that year. The eulogistic poem by his friend, George Fabricius, is dated in 1551.

The publication was apparently long delayed by the preparation of the woodcuts; and, according to Mathesius,[18] many sketches for them were prepared by Basilius Wefring. In the preface of De Re Metallica, Agricola does not mention who prepared the sketches, but does say: "I have hired illustrators to delineate their forms, lest descriptions which are conveyed by words should either not be understood by men of our own times, or should cause difficulty to posterity." In 1553 the completed book was sent to Froben for publication, for a letter[19] from Fabricius to Meurer in March, 1553, announces its dispatch to the printer. An interesting letter