Pliny the Younger (A.D. 62?–c.A.D. 113). Letters. The Harvard Classics. 1909–14.
XXIV. To the Emperor Trajan
I AM informed by a letter from the king of Sarmatia that there are certain affairs of which you ought to be informed as soon as possible. In order, therefore, to hasten the despatches which his courier was charged with to you, I granted him an order to make use of the public post.