- How sure this is
- 40% sureLots of sources credit Marcus Aurelius with this, and they agree with each other. The book or the speech it first came from hasn't turned up yet.
- What turned up
- Popular modern paraphrase of Meditations VIII.47 (trans. George Long, 1862): "it is not this thing that disturbs thee, but thy own judgement about it." Condensed wording is not Long's or any primary translation — paraphrase class, stays likely.