Letter 95 — On the Usefulness of Basic Principles (§65)

“Posidonius holds that not only precept-giving (there is nothing to prevent my using this word), but even persuasion, consolation, and encouragement, are necessary. To these he adds the investigation of causes (but I fail to see why I should not dare to call it aetiology, since the scholars who mount guard over the Latin language thus use the term as having the right to do so). He remarks that it will also be useful to illustrate each particular virtue; this science Posidonius calls ethology, while others call it characterization. It gives the signs and marks which belong to each virtue and vice, so that by them distinction may be drawn between like things.”