Pliny, in his letters to Trajan, though reputed an excellent prince, addressed him as only sir or master, and he wrote many years after the death of Paul.
Athenagoras, in addressing his book, in times posterior to these, to the emperors M.Aurelius Antoninus, and L.Aurelius Commodus, addresses them only by the title of "great princes." In short titles were not in use.

They did not creep in, so as to be commonly used, till after the statues of the emperors had begun to be worshipped by the military as a legal and accustomary homage.

The terms "eternity and divinity" with others were then ushered in, but these were confined wholly to the emperors themselves.

In the time of Constantine we find the title of illustrious.

This was given to those princes, who had distinguished themselves in war, but it was not continued to their descendants.