The virtue of Marcus Aurelius Antoninus was of a severer and more laborious kind. It was the well-earned harvest of many a learned conference, of many a patient lecture, and many a midnight lucubration. At the age of twelve years, he embraced the rigid system of the Stoics, which taught him to submit his body to his mind, his passions to his reason; to consider virtue as the only good, vice as the only evil, all things external as things indifferent.