Address & Argument
Aphorism
A short statement of a general observation or principle. Its brevity can make it memorable, but does not establish that the claim is true.
"It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife." — Austen (ironic aphorism)
Don't confuse it with Irony. A maxim instructs conduct; an epigram jokes; the aphorism claims truth. Austen's is an aphorism wearing irony.
Examples
A promise is easy to make and costly to keep.
The compact, freestanding statement presents a general observation about promises.
The rest of the family
Rhetorical Question Apostrophe Invocation Enthymeme Correctio / Epanorthosis Parrhesia Metabasis Amplificatio Aporia Enargeia / Vivid Specificity