How we cite our quotes: Section.Part (if applicable).Paragraph
Quote #7
The necessity of justice to the support of society is the sole foundation of that virtue; and since no moral excellence is more highly esteemed, we may conclude that this circumstance of usefulness has, in general, the strongest energy, and most entire command over our sentiments. It must, therefore, be the source of a considerable part of the merit ascribed to humanity, benevolence, friendship, public spirit, and other social virtues of that stamp; as it is the sole source of the moral approbation paid to fidelity, justice, veracity, integrity, and those other estimable and useful qualities. (III.II.27)
We keep coming back to the same theme: usefulness. The above quote sums up the importance of this quality and how big a role it plays in our lives. Just take a look at the virtues that Hume lists. They're all valuable and they're all pleasing but they have something else in common. Yep, they're all useful (if Hume guested on Sesame Street, this would definitely be the word of the day).
Quote #8
It is indeed observable, that, among all uncultivated nations, who have not as yet had full experience of the advantages attending beneficence, justice, and the social virtues, courage is the predominant excellence; what is most celebrated by poets, recommended by parents and instructors, and admired by the public in general. (VII.15)
We know that justice and the other social virtues are valued in the society we live in today. But, if we step outside modern, industrial society, we find that this isn't always the case. What about primitive societies and nations that aren't fully civilized? Here, different values are seen as useful, with courage being the cream of the crop.
Quote #9
When Oedipus killed Laius, he was ignorant of the relation, and from circumstances, innocent and involuntary, formed erroneous opinions […] But when Nero killed Agrippina, all the relations between himself and the person, and all the circumstances of the fact, were previously known to him; but the motive of revenge, or fear, or interest, prevailed in his savage heart over the sentiments of duty and humanity. (AI.12)
Okay, so crimes don't come much more serious than murder, but juries still have to weigh up the motive. In some cases, we're dealing with cold-blooded murder driven by revenge, self-interest, or all sorts of ridiculous reasons. In other cases, though, the killer may be ignorant of how things really are. Both are serious acts, but, using examples from mythology, Hume highlights the difference between making a big mistake and being a whacked-out murderer who's lost any sense of humanity.