Plutarch, Caius Marcius Coriolanus
Bernadotte Perrin, Ed.

11. When the multitude had ceased shouting their applause, Cominius took up the word again and said: ‘Ye cannot, indeed, my fellow-soldiers, force these gifts of yours upon the man, when he does not accept them and is unwilling to take them; but there is a gift which he cannot refuse when it is offered. Let us give him this gift, and pass a vote that he be surnamed Coriolanus, unless, indeed, before such act of ours, his exploit has itself given him this name.’ Thence came his third name of Coriolanus.¹

[2] From this it is perfectly clear that Caius was the proper name; that the second name, in this case Marcius, was the common name of family or clan; and that the third name was adopted subsequently, and bestowed because of some exploit, or fortune, or bodily feature, or special excellence in a man. So the Greeks used to give surnames from an exploit, as for instance, Soter² and Callinicus; or from a bodily feature, as Physcon and Grypus; or from a special excellence, as Euergetes and Philadephus; or from some good fortune, as Eudaemon, the surname of the second Battus. [3] And some of their kings have actually had surnames given them in mockery, as Antigonus Doson and Ptolemy Lathyrus. Surnames of this sort were even more common among the Romans. For instance, one of the Metelli was called Diadematus, because for a long time he suffered from a running sore and went about with a bandage on his forehead; another member of this family was called Celer, because he exerted himself to give the people funeral games of gladiators within a few days of his father's death, and the speed and swiftness of his preparations excited astonishment.³ [4] And at the present day some of them are named from casual incidents at their birth, Proculus, for instance, if a child is born when his father is away from home; or Postumus, if after his death; and when one of twin children survives, while the other dies, he is called Vopiscus. Moreover, from bodily features they not only bestow such surnames as Sulla, Niger, and Rufus, but also such as Caecus and Claudius. And they do well thus to accustom men to regard neither blindness nor any other bodily misfortune as a reproach or a disgrace, but to answer to such names as though their own. This topic, however, would be more fittingly discussed elsewhere.