The Roman History · Amm. 14.6.23

And since among them, as is natural in a city so great as to be the metropolis of the world, diseases attain to such an insurmountable degree of violence, that all the skill of the physician is ineffectual even to mitigate them; a certain assistance and means of safety has been devised, in the rule that no one should go to see a friend in such a condition, and to a few precautionary measures a further remedy of sufficient potency has been added, that men should not readmit into their houses servants who have been sent to inquire how a man's friends who may have been seized with an illness of this kind are, until they have cleansed and purified their persons in the bath. So that a taint is feared, even when it has only been seen with the eyes of another.

Ammianus Marcellinus · translated by C. D. Yonge · 1911 reprint
C. D. Yonge translation (preface dated February 1862); G. Bell and Sons, 1911; Project Gutenberg #28587
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