3 ideas
Historical anecdotes are stripped from their chronological context and filed under moral headings such as gratitude, cruelty, moderation, and severity, so a speaker can pull a ready precedent for whatever virtue or vice the case turns on. The organizing principle is utility in argument rather than historical sequence. Each story becomes a portable proof that a given behavior has been praised or condemned before.
Within each moral category, Roman cases come first and carry the weight, and foreign cases (Greek, Persian, Carthaginian) follow as secondary confirmation. The ordering itself makes an argument: virtue is presented as native to one's own tradition, with outsiders serving as corroboration or contrast. Reading any collection for which examples are placed first and which are placed second reveals whose conduct is being set up as the standard.
The consul Titus Manlius Torquatus had his own son beheaded for leaving the ranks to fight a single combat against orders, even though the son won. The anecdote is offered as a model of military discipline: a successful outcome does not excuse breaking a command, and the commander proves that the rule is absolute by applying it at the highest personal cost. The story frames discipline as the thing that preserves the state, ranked above both family affection and battlefield glory.