Marcus Aurelius
Meditations 2.15
Remember that all is opinion. For what was said by the Cynic Monimus is manifest: and manifest too is the use of what was said, if a man receives what may be got out of it as far as it is true.
Marcus Aurelius, Meditations 2.15, translated by George Long
Remember that everything is but what we think it. For obvious indeed is the saying fathered on Monimus the Cynic, obvious too the utility of what was said, if one accept the gist of it as far as it is true.
Marcus Aurelius, Meditations 2.15, translated by C. R. Haines