Letters 66.10

The good, in every instance, is subject to these same laws. The advantage of the state and that of the individual are yoked together; indeed it is as impossible to separate them as to separate the commendable from the desirable. Therefore, virtues are mutually equal; and so are the works of virtue, and all men who are so fortunate as to possess these virtues.

Seneca, Letters to Lucilius 66.10, translated by Richard Mott Gummere