Extract from the Thoughts of Emperor Marcus Aurelius Antoninus
Book IV, 31-33

31. Love the art, poor as it may be, which thou hast learned, and be content with it; and pass through the rest of life like one who has intrusted to the gods with his whole soul all that he has, making thyself neither the tyrant nor the slave of any man.

32. Consider for example, the times of Vespasian. Thou wilt see all these things, people marrying, bringing up children, sick, dying, warring, feasting, trafficking, cultivating the ground, flattering, obstinately arrogant, suspecting, plotting, wishing for some to die, grumbling about the present, loving, heaping up treasure, desiring consulship, kingly power. Well, then, that life of these people no longer exists at all. Again, remove to the times of Trajan. Again, all is the same. Their life too is gone. In like manner view also the other epochs of time and of whole nations, and see how many after great efforts soon fell and were resolved into the elements. But chiefly thou shouldst think of those whom thou hast thyself known distracting themselves about idle things, neglecting to do what was in accordance with their proper constitution, and to hold firmly to this and to be content with it. And herein it is necessary to remember that the attention given to everything has its proper value and proportion. For thus thou wilt not be dissatisfied, if thou appliest thyself to smaller matters no further than is fit.

33. The words which were formerly familiar are now antiquated: so also the names of those who were famed of old, are now in a manner antiquated, Camillus, Caeso, Volesus, Leonnatus, and a little after also Scipio and Cato, then Augustus, then also Hadrianus and Antoninus. For all things soon pass away and become a mere tale, and complete oblivion soon buries them. And I say this of those who have shone in a wondrous way. For the rest, as soon as they have breathed out their breath, they are gone, and no man speaks of them. And, to conclude the matter, what is even an eternal remembrance? A mere nothing. What then is that about which we ought to employ our serious pains? This one thing, thoughts just, and acts social, and words which never lie, and a disposition which gladly accepts all that happens, as necessary, as usual, as flowing from a principle and source of the same kind.

Emperor Marcus Aurelius Antoninus
To Himself (Τὰ εἰς ἑαυτόν),
trans. George Long (1862), ed. E. Ginn
[WikiSource]

Evagrius Scholasticus, Ecclesiastical History, IV, XXXII:

Justinian I
Justinianus I
Ιουστινιανός I

"There was also another quality latent in the character of Justinian, a depravity which exceeded any bestiality which can be imagined; and whether this was a defect of his natural character, or whether it was the outgrowth of cowardice and fear, I am unable to say, but in any case it manifested itself as a result of the popular Nika Insurrection. For he seemed to be absolutely devoted to one of the two Factions, the Blues namely, and to such a degree that these actually used to murder their opponents in cold blood in broad daylight and in the middle of the city, and not only did they suffer no penalty, but they actually were counted worthy of prizes of honour. And they were permitted even to enter houses and to gather as plunder the valuables therein and to force the inhabitants to pay for their own lives. And if any of the magistrates tried to stop them, he thereby endangered his own life. Thus, for instance, a certain man administering the government of the East, because he disciplined with stripes some of the unruly element, was himself flogged in the very middle of the city and roughly handled. And Callinicus, the Governor of Cilicia, because he inflicted the punishment of the law upon two Cilician murderers, Pautus and Faustinus, who had assaulted him and made an attempt upon his life, was impaled, thus paying the penalty for his correct judgment and his support of the laws. Consequently the members of the opposite Faction went off into exile, and being received by no one at all, but being driven away from every place like polluted creatures, they proceeded to waylay travellers, both robbing and murdering them, so that every place was full of violent deaths and highway robbery and the other sorts of crime. Occasionally too he went over to the opposite side and began to destroy them, allowing the laws which he had abandoned to run riot through the cities like barbarians. And to tell of all these matters in detail, neither words nor time would suffice; yet these examples are sufficient to furnish evidence for all the rest."

Evagrius Scholasticus (also known as Epiphaneia, Ex-Præfectus)
Ecclesiastical History, IV, XXXII - [Tertulian | WorldCat ]
A younger contemporary of Procopius and of Justinian (c. 536‑594)

Cp. Procopius, The Secret History, tr. by Richard Atwater (1927) [Sacred-Texts]
[WikiSource]