To this brief description one more curious fact remains to be added,—namely, that in almost all, if not in all, the Roman medicine-stamps hitherto discovered, the medicines inscribed upon them are drugs for affections of the eye and its appendages; and the diseases, when specified upon them, are always ophthalmic diseases. Hence it may, with great probability, be concluded, that either these stamps were used by oculists alone, or they were used by the general medical practitioner in marking his eye-medicines only. On this account some authors have not inaptly described them under the special designation of Roman Ophthalmic or Oculist stamps. The number of the stamps that have already been discovered amply proves that ophthalmic diseases must have been extremely frequent in the sites of the old Roman colonies spread throughout western Europe; and although only three such oculist-stamps are as yet described as having been found within the confines of Italy itself,[436] yet the frequent references to individual oculists at Rome by Celsus, Galen, and others, and the elaborate descriptions of eye-diseases left us by the various Greek and Roman medical authors, who practised in the Eternal City during the time of the empire, alike testify to the fact, that these diseases were also sufficiently common in the Roman capital, and that many of the fellow-citizens of Horace could probably personally apply the well-known description which the poet gives of himself:— Hic oculis ego nigra meis Collyria lippus Illinere. Galen, Celsus, Ætius, Paulus Ægineta, etc., all describe the different diseases of the eye with care and minuteness; and the Roman practitioners had evidently studied these affections, and their specific distinctions, with no small degree of attention. In modern times medical literature has been enriched with more complete and elaborate monographs upon the diseases of the eye, than upon the diseases of any other single organ of the body. But, perhaps, few of these monographs describe a larger number of ophthalmic diseases than was professed to be known and discriminated in those distant times when Galen wrote and practised. This author, in the 16th chapter of his book, entitled _Introductio seu Medicus_ enumerates and defines nosologically not less than one hundred and twenty-four diseases to which the eye and its appendages are liable.[437]