"Marcus Aurelius does not direct his reflections to others but only to himself. The “”Memoirs“” are not a lesson for an ideal or real disciple (as Seneca's “'Letters to Lucilius”' were), but a continuous effort to remind “'himself”' of the philosophical cornerstones that alone can guarantee him serenity and inner peace. They therefore have a dramatic tone that is lacking in other ancient and modern moral works. Marcus Aurelius' interlocutor is only himself: Marcus Aurelius, emperor and man. Only within himself does he believe he can find the law of truth and goodness. Seeking solitude is useless, he says; one must withdraw into oneself because only in the depths of one's soul can tranquillity and truth be found. This attitude, which was adopted by the Christian world, is the fundamental leitmotif of Marcus Aurelius's “Memoirs”. In himself, man finds the reason with which divine providence has ordered the universe, and the criterion of truth and moral conduct. But by withdrawing into himself, man does not find himself in isolation: reason binds him to all men with whom he shares it."
January 1, 1970
https://en.wikiquote.org/wiki/Marcus_Aurelius