Sourced
No longer talk at all about the kind of man that a good man ought to be, but be such.
Popularly shortened to "Waste no more time arguing what a good man should be. Be one."
Source: Meditations 10.16, tr. George Long
Authors / Marcus Aurelius
The emperor's Meditations were private notes to himself, never meant for publication. We quote George Long's 19th-century translation; many viral "Marcus Aurelius quotes" are modern paraphrases that drift far from what he wrote.