consultors of the Papacy in all matters relating to Germany. During the last twenty-five years of his life in all the relations of the Holy See to Germany, appeal was constantly made to the wisdom, the experience, and the thoroughly conservative, yet foreseeing, judgment of this son of the people, whose education had lifted him up to be one of the leaders of men in Europe.

It was during this time that he wrote most of his books on mathematics, which have earned for him a prominent place in Cantor's "History of Mathematics," about a score of pages being devoted to his work. Much of his thinking was done while riding on horseback or in the rude vehicles of the day on the missions to which he was sent as Papal Legate. He is said to have worked out the formula for the cycloid curve while watching the path described by flies that had lighted on the wheels of his carriage, and were carried forward and around by them. His scientific books, though they included such startling anticipations of Copernicus' doctrines as we have already quoted (Copernicus did not publish the first sketch of his theory for more than a quarter of a century after Cusanus' death), far from disturbing his ecclesiastical advancement or injuring his career as a churchman, seem actually to have been considered as additional reasons for considering him worthy of confidence and consultation.

As the result of his careful studies of conditions in Germany, he realized very clearly how much of unfortunate influence the political status of the German people, with their many petty rulers and the

hampering of development consequent upon the trivial rivalries, the constant bickerings, and the inordinate jealousies of these numerous princelings, had upon his native country. Accordingly, towards the end of his life he sketched what he thought would be the ideal political status for the German people. As in everything that he wrote, he went straight to the heart of the matter and, without mincing words, stated just exactly what he thought ought to be done. Considering that this scheme of Cusanus for the prosperity and right government of the German people was not accomplished until more than four centuries after his death, it is interesting, indeed, to realize how this clergyman of the middle of the fifteenth century should have come to any such thought. Nothing, however, makes it clearer than this, that it is not time that fosters thinking, but that great men at any time come to great thoughts. Cusanus wrote:

"The law and the kingdom should be placed under the protection of a single ruler or authority. The small separate governments of princes and counts consume a disproportionately large amount of revenue without furnishing any real security. For this reason we must have a single government, and for its support we must have a definite amount of the income from taxes and revenues yearly set aside by a representative parliament and before this parliament (reichstag) must be given every year a definite account of the money that was spent during the preceding year.

Cusanus' life and work stand, then, as a type of the accomplishment, the opportunities, the power of thought, the practical scholarship, the mathematical

accuracy, the fine scientific foresight of a scholar of the fifteenth century. For us, in medicine, it is interesting indeed to realize that it is from a man of this kind that a great new departure in medicine with regard to the employment of exact methods of diagnosis had its first suggestion in modern times. The origin of that suggestion is typical. It has practically always been true that it was not the man who had exhausted, or thought that he had done so, all previous medical knowledge, who made advances in medicine for us. It has nearly always been a young man early in his career, and at a time when, as yet, his mind was not overloaded with the medical theories of his own time. Cusanus was probably not more than thirty when he made the suggestion which represents the first practical hint for the use of laboratory methods in modern medicine. It came out of his thoughtful consideration of medical problems rather than from a store of garnered information as to what others thought. It is a lesson in the precious value of breadth of education and serious training of mind for real progress at all times.

XIV

BASIL VALENTINE, LAST OF THE ALCHEMISTS, FIRST OF THE CHEMISTS

"Fieri enim potest ut operator erret et a via regia deflectat, sed ut erret natura quando recte tractatur fieri non potest."

"For it is quite possible that the physician should err and be turned aside from the straight (royal) road, but that nature when she is rightly treated should err is quite impossible."

This is one of the preliminary maxims of a treatise on medicine written by a physician born not later than the first half of the fifteenth century, and who may have lived even somewhat earlier. We are so prone to think of the men of that time as utterly dependent on authority, not daring to follow their own observation, suspecting nature, and almost sure to be convinced that only by going counter to her could success in the treatment of disease be obtained, that it is a surprise to most people to find how completely the attitude of mind, that is supposed to be so typically modern in this regard, was anticipated full four centuries ago. There are other expressions of this same great physician and medical writer, Basil Valentine, which serve to show how faithfully he strove with the lights that he had to work out the treatment of patients, just as we do now, by trying to find out nature's way, so as to

imitate her beneficent processes and purposes. It is quite clear that he is but one of many faithful, patient observers and experimenters-true scientists in the best sense of the word-who lived in all the centuries of the Middle Ages.

Speculations and experiments with regard to the elixir of life, the philosopher's stone, and the transmutation of metals, are presumed to have filled up all the serious interests of the alchemists, supposed to be almost the only scientists of those days. As a matter of fact, however, men were making original observations of profound significance, and these were considered so valuable by their contemporaries that, though printing had not yet been invented, even the immense labor involved in the manifold copying of large folio volumes by the slow hand process did not suffice to deter them from multiplying the writings of these men so numerously that they were preserved in many copies for future generations, until the printing press came to perpetuate them.

Of this there is abundant evidence in the preceding pages as regards medicine, and, above all, surgery, while a summary of accomplishments of workers in other departments will be found in Appendix II," Science at the Medieval Universities."

At the beginning of the twentieth century, with some of the supposed foundations of modern chemistry crumbling to pieces under the influence of the peculiarly active light thrown upon our nineteenth century chemical theories by the discovery of radium, and our observations on radio-active elements generally, there is a reawakening of interest