The empty pageant; a stage play; flocks of sheep, herds of cattle; a tussle of spearmen; a bone flung among a pack of curs; a crumb tossed into a pond of fish; ants, loaded and laboring; mice, scared and capering; puppets, jerking on their strings — that is life. In the midst of it all you must take your stand, good-temperedly and without disdain, yet always aware that a man’s worth is no greater than the worth of his ambitions.

[Πομπῆς κενοσπουδία, ἐπὶ σκηνῆς δράματα, ποίμνια, ἀγέλαι, διαδορατισμοί, κυνιδίοις ὀστάριον ἐρριμμένον, ψωμίον εἰς τὰς τῶν ἰχθύων δεξαμενάς, μυρμήκων ταλαιπωρίαι καὶ ἀχθοφορίαι, μυιδίων ἐπτοημένων διαδρομαί, σιγιλλάρια νευροσπαστούμενα. χρὴ οὖν ἐν τούτοις εὐμενῶς μὲν καὶ μὴ καταφρυαττόμενον ἑστάναι, παρακολουθεῖν μέντοι, ὅτι τοσούτου ἄξιος ἕκαστός ἐστιν, ὅσου ἄξιά ἐστι ταῦτα περὶ ἃ ἐσπούδακεν.]

Marcus Aurelius (AD 121-180) Roman emperor (161-180), Stoic philosopher

Meditations, Book 7, #3 [tr. Staniforth (1964)]
    (Source)

Original Greek. Alternate translations:

Public shows and solemnities with much pomp and vanity, stage plays, flocks and herds; conflicts and contentions: a bone thrown to a company of hungry curs; a bait for greedy fishes; the painfulness, and continual burden-bearing of wretched ants, the running to and fro of terrified mice: little puppets drawn up and down with wires and nerves: these be the objects of the world. among all these thou must stand steadfast, meekly affected, and free from all manner of indignation; with this right ratiocination and apprehension; that as the worth is of those things which a man doth affect, so is in very deed every man's worth more or less.
[tr. Casaubon (1634)]

Gazing after triumphs, and cavalcades; the diversions of the stage; farms well stocked with flocks and herds; contests for victory in the field; these are the little pleasures, and concerns of mortals. Would you have a farther illustration, and see an image of them elsewhere? Fancy then that you saw two or three whelps quarrelling about a bone; fishes scrambling for a bait; pismires in a peck of troubles about the carriage of a grain of wheat; mice frighted out of their wits; and scouring cross the room; poppets dancing upon a wire, etc. And after all, though humane life is but ordinary, and trifling, a wise man must be easy and good-humored, and not grow splenetic, or haughty upon the contemplation. Remembering notwithstanding, that the true bulk and bigness of a man, is to be measured by the size of his business, and the quality of his inclinations.
[tr. Collier (1701)]

The idle business of show, plays on the stage, flocks of sheep, herds, exercises with spears, a bone cast to little dogs, a bit of bread into fishponds, laborings of ants and burden-carrying, runnings about of frightened little mice, puppets pulled by strings—[all alike]. It is thy duty then in the midst of such things to show good humor and not a proud air; to understand however that every man is worth just so much as the things are worth about which he busies himself.
[tr. Long (1862)]

Gazing after shows, the diversions of the stage, farms well stocked with flocks and herds, contests for victory in the field are all much the same. So, too, a bone thrown to puppies, fishes scrambling for a bait, ants laboriously carrying a grain of wheat, mice frighted out of their wits and running away, puppets danced upon a wire. And in the midst of them a wise man must be good-humored, and not grow haughty in the contemplation. Remembering, notwithstanding, that the true worth of a man is to be measured by the objects he pursues.
[tr. Zimmern (1887)]

A procession's vain pomp, plays on a stage, flocks, herds, sham fights, a bone thrown to puppies, a crumb into fishponds, toiling and moiling of ants carrying their loads, scurrying of startled mice, marionettes dancing to strings. Well, then, you must stand up in all this, kindly and not carrying your head proudly; yet understand that every man is worth just so much as the worth of what he has set his heart upon.
[tr. Farquharson (1944)]

Pointless bustling of processions, opera arias, herds of sheep and cattle, military exercises. A bone flung to pet poodles, a little food in the fish tank. The miserable servitude of ants, scampering of frightened mice, puppets jerked on strings. Surrounded as we are by all of this, we need to practice acceptance. Without disdain. But remembering that our own worth is measured by what we devote our energy to.
[tr. Hays (2003)]