Letters 95.35

If we would hold men firmly bound and tear them away from the ills which clutch them fast, they must learn what is evil and what is good. They must know that everything except virtue changes its name and becomes now good and now bad. Just as the soldier’s primary bond of union is his oath of allegiance and his love for the flag, and a horror of desertion, and just as, after this stage, other duties can easily be demanded of him, and trusts given to him when once the oath has been administered; so it is with those whom you would bring to the happy life: the first foundations must be laid, and virtue worked into these men. Let them be held by a sort of superstitious worship of virtue; let them love her; let them desire to live with her, and refuse to live without her.

Seneca, Letters to Lucilius 95.35, translated by Richard Mott Gummere