On this point we believe it is necessary to correct an error into which Dr. Geist-Jacobi has fallen. At the beginning of his very valuable article on Walter Hermann Ryff[280] he says: “In the fifth century of the Christian era, the iatrosophist Adamantius of Alexandria published an exclusively odontalgic work, of which, however, we only know the title.” The same he repeats in his _History of Dental Art_ (pp. 55 and 56), without, however, giving us any proof of his statement. “Of the odontologic treatise of Adamantius,” he says, “unfortunately the title alone is known to us, and even that has reached us indirectly, that is, by means of Ætius; it is of the following tenor.” Now, whoever takes the trouble to translate these Greek words will easily perceive that they do not constitute one title, but two distinct ones (which even Dr. Geist-Jacobi has had to unite by the conjunction _and_). These, however, are nothing more than the titles of two chapters of the _Tetrabiblos_ of Ætius, as anyone may see for himself by turning over the pages of this work either in the Greek original, or in the beautiful Latin translation of Giano Cornario (Venice, 1553). In this great composition of Ætius dental diseases are treated of in Chapters XXVII to XXXV of Sermo IV, Tetrabiblos II; and the two Greek titles above referred to are the titles of Chapters XXVII and XXXI. In the translation of Giano Cornario they read as follows: _Cura dentium a calido morbo doloroso affectorum, ex Adamantio sophista_ (cure of teeth affected by warm, painful disease, according to Adamantius the sophist). _Cura dentium a siccitate dolore affectorum, ex Adamantio sophista_ (cure of teeth affected by pain from dryness, according to Adamantius the sophist). The work of Adamantius, from which Ætius took the contents of the chapters thus entitled, is lost to us, but we have no reason, and not even the least indication, for supposing that this work was a treatise on dental diseases, and not one on general medicine. It is absurd to consider the above-mentioned titles as belonging to an odontological monograph, on the one hand, because, admitting for a moment the existence of such a work, it should have had but one title and not two, and on the other hand, because it is by no means to be supposed that a great and wise physician, such as Adamantius undoubtedly was, should have had the whim to write a book, not on dental disease or on dental pains in general, but only and exclusively on dental pains caused by heat or by dryness. What reason would there have been for not extending the treatment of the subject to those cases of odontalgia resulting from humidity or from cold, that is, from causes as common and, according to the ideas of that time, very frequently associated with one of the first two (as humidity with heat, and cold with dryness)?