Gratitude is not only the greatest of virtues, but the parent of all others. - Cicero

We don't practise generosity in order to secure gratitude, nor do we invest our gifts in the hope of a favourable return. Rather, it is nature that inclines us towards generosity. Just so, we don't seek friendship with an expectation of gain, but regard the feeling of love as its own reward.

Una nación puede sobrevivir a sus locos y hasta a sus ambiciosos, pero no puede sobrevivir a la traición intestina

its underlying principles are in such close harmony with the absolute and eternal right that they can never become obsolete. At the same time, the division and arrangement of the treatise give it, so far as I know, the precedence over all other ethical treatises ancient or modern.