Cicero on Morals and Moral Duties

"Although philosophy offers many problems, both important and useful, that have been fully and carefully discussed by philosophers, those teachings which have been handed down on the subject of moral duties seem to have the widest practical application. For no phase of life, whether public or private, whether in business or in the home, whether one is working on what concerns oneself alone or dealing with another, can be without its moral duty; on the discharge of such duties depends all that is morally right, and on their neglect all that is morally wrong in life.

Moreover, the subject of this inquiry is the common property of all philosophers; for who would presume to call himself a philosopher, if he did not inculcate any lessons of duty? But there are some schools that distort all notions of duty by the theories they propose touching the supreme good and the supreme evil. For he who posits the supreme good as having no connection with virtue and measures it not by a moral standard but by his own interests — if he should be consistent and not rather at times over-ruled by his better nature, he could value neither friendship nor justice nor generosity; and brave he surely cannot possibly be that counts pain the supreme evil, nor temperate he that holds pleasure to be the supreme good."
From
DE OFFICIIS
By Marcus Tullius Cicero

Translated by Walter Miller.
Loeb edn.
Cambridge: Harvard University Press,
1913