Plutarch, De communibus notitiis adversus Stoicos
Goodwin, Ed.

Wherefore I would willingly ask, in what vice is profitable to the universe. Not surely in respect of heavenly things, and such as are divine by nature. For it would be ridiculous to say, that if there had not arisen, or were not amongst men, malice and covetousness and lying, or that if we did not rob, plunder, slander, and murder one another, the sun would not run his appointed course, the world enjoy its seasons and periods of time, or the earth, [p. 387] which is seated in the midst of the universe, afford the principles of the wind and rain. It remains then, that the existence of vice must be profitable for us and our affairs; and that perhaps these men mean. Are we more healthy for being vicious, or do we more abound with necessaries? Or does vice contribute any thing to our beauty and strength? They say, no. But where on earth is virtue to be found? Is it then only a name, and a visionary opinion of night-walking sophisters, and not a reality lying conspicuous to all, like vice, so that we cannot partake of any thing as unprofitable,¹ ... but least, 0 ye Gods! of virtue, for which we were created? Is it not then absurd, that the utensils of the husbandman, mariner, and charioteer should be serviceable and aiding towards his intended end, whilst that which was by God made for virtue destroys and corrupts virtue? But perhaps it is time now to leave this point, and pass to another.