Whether your neighbor acts ignorantly or with knowledge remember he is your countryman

The George Long translation of 1862:

Hasten to examine thy own ruling faculty and that of the universe and that of thy neighbour,  thy own that thou mayest make it just, and that of the universe, that thou mayest remember of what thou art a part, and that of thy neighbour, that thou mayest know whether he has acted ignorantly or with knowledge, and that thou mayest also consider that his ruling faculty is akin to thine. Marcus Aurelius.  Meditations. Book 9.

Chrystal's 2017 rendering based on the Foulis translation of 1742:

Make swift appeal to your own ruling part, to that of the Universe, and to his who has offended you. To your own, that you may make it a mind disposed to justice, to that of the Universe, that you may remember of what you are a part, and to his, that you may know whether he has acted in ignorance or by design, and that you may also reflect that he is your kinsman. Marcus Aurelius.  Meditations. Book 9.

Image: Detail from the fresco depicting the battle between the Horatii and the Curiatii by Giuseppe Cesari, 1612-1613, that I photographed at the Captioline Museum in Rome.