Dr. F. A. Reuss, of the University of Wuertzburg, at the conclusion of his _Prolegomena_ to the _Physica_ published in Migne's _Patrologia_, expresses himself as follows regarding the writings and medical knowledge of the illustrious abbess of Bingen: "Among all the saintly _religieuses_ who, during the Middle Ages, practiced medicine or wrote treatises on it, the first, without contradiction, is Hildegard. According to the monk Theodoric, who was an eye witness, she had to so high a degree the gift of healing that no sick person had recourse to her without being restored to health. There is among the books of this prophetic virgin a work which treats of physics and medicine. Its title is _De Natura Nominis Elementorum Diversarumque Creaturarum_, and it embodies, as the same Theodoric fully explains, the secrets of nature which were revealed to the saint by the prophetic spirit. All who wish to write the history of the medical and natural sciences should read this book, in which the holy virgin, initiated into all the secrets of nature which were then known, and having received special assistance from above, thoroughly examines and scrutinizes all that which was, until then, buried in darkness and concealed from the eyes of mortals. It is certain that Hildegard was acquainted with many things of which the doctors of the Middle Ages were ignorant, and which the investigators of our own age, after rediscovering them, have announced as something entirely new."[190] The life and works of St. Hildegard throw a flood of light on many subjects that have long been veiled in mystery. It explains why the convents of the later Middle Ages were so famed as curative centers and why the sick flocked to them for relief from far and near. It reveals the real agencies employed in effecting the extraordinary cures that were reported in so many religious houses--cures so extraordinary that they were usually regarded by the multitude as miraculous--and discloses the secret of the success of so many nuns in the alleviation of physical and mental sufferings. It was not because they were thaumaturges, but because they were good nurses, and because of their thorough knowledge of the healing art, that they were able to diagnose and prescribe for diseases of all kinds with a success which, in the estimation of the multitude, savored of the supernatural. There was also another reason for the fame of convents as sanctuaries of health. They were usually situated in healthy locations where there was an abundance of pure water, fresh air and cheerful sunshine. Then there were likewise a wholesome diet, good sanitary conditions, and, above all, regularity of life.