Meditation 4.32
32. Call to mind by way of example the time of Vespasian: you will see everything the same: men marrying, bringing up children, falling ill, dying, fighting, feasting, trading, farming, flattering, asserting themselves, suspecting, plotting, praying for another's death, murmuring at the present, lusting, heaping up riches, setting their heart on offices and thrones. And now that life of theirs is no more and nowhere.
Again pass on to the time of Trajan; again everything the same. That life, too, is dead. In like manner contemplate and behold the rest of the records of times and whole nations; and see how many after their struggles fell in a little while and were resolved into the elements. But most of all you must run over in mind those whom you yourself have known to be distracted in vain, neglecting to perform what was agreeable to their own constitution, to hold fast to this and to be content with this. And here you are bound to remember that the attention paid to each action has its own worth and proportion, only so you will not be dejected if in smaller matters you are occupied no farther than was appropriate.