Antoninus has recorded in his first book the names of his teachers, and the obligations which he owed to each of them.  The way in which he speaks of what he learned from them might seem to savor of vanity or self-praise, if we look carelessly at the way in which he has expressed himself; but if any one draws this conclusion, he will be mistaken.  Antoninus means to commemorate the merits of his several teachers, what they taught, and what a pupil might learn from them.  Besides, this book, like the eleven other books, was for his own use; and if we may trust the note at the end of the first book, it was written during one of M. Antoninus’ campaigns against the Quadi, at a time when the commemoration of the virtues of his illustrious teachers might remind him of their lessons and the practical uses which he might derive from them.

Among his teachers of philosophy was Sextus of Chaeroneia, a grandson of Plutarch.  What he learned from this excellent man is told by himself (i. 9).  His favorite teacher was Q. Junius Rusticus (i. 7), a philosopher, and also a man of practical good sense in public affairs.  Rusticus was the adviser of Antoninus after he became emperor.  Young men who are destined for high places are not often fortunate in those who are about them, their companions and teachers; and I do not know any example of a young prince having had an education which can be compared with that of M. Antoninus.  Such a body of teachers distinguished by their acquirements and their character will hardly be collected again; and as to the pupil, we have not had one like him since.

Hadrian died in July A.D. 138, and was succeeded by Antoninus Pius.  M. Antoninus married Faustina, his cousin, the daughter of Pius, probably about A.D. 146, for he had a daughter born in 147.  He received from his adoptive father the title of Caesar, and was associated with him in the administration of the state.  The father and the adopted son lived together in perfect friendship and confidence.  Antoninus was a dutiful son, and the emperor Pius loved and esteemed him.

Antoninus Pius died in March, A.D. 161.  The Senate, it is said, urged M. Antoninus to take the sole administration of the empire, but he associated with himself the other adopted son of Pius, L. Ceionius Commodus, who is generally called L. Verus.  Thus Rome for the first time had two emperors.  Verus was an indolent man of pleasure, and unworthy of his station.  Antoninus however bore with him, and it is said Verus had sense enough to pay to his colleague the respect due to his character.  A virtuous emperor and a loose partner lived together in peace, and their alliance was strengthened by Antoninus giving to Verus for wife his daughter Lucilla.

The reign of Antoninus was first troubled by a Parthian war, in which Verus was sent to command; but he did nothing, and the success that was obtained by the Romans in Armenia and on the Euphrates and Tigris was due to his generals.  This Parthian war ended in A.D. 165.  Aurelius and Verus had a triumph (A.D. 166) for the victories in the East.  A pestilence followed, which carried off great numbers in Rome and Italy, and spread to the west of Europe.