If. Marcus Aurelius 3.12

Ethics exist because we act. A rational action is one that occurs because we engage it deliberately, with a plan in mind. That plan necessarily requires us to consider when and how our action should end. No real action in the realm of rational ethics is one that we engage forever, without end. The potential for some end is always there; eventually it becomes actual. This is mortality. Marcus wants to engage it rationally, deliberately, with a pure spirit (δαίμονα καθαρὸν, as he says).

Ἐὰν τὸ παρὸν ἐνεργῇς ἑπόμενος τῷ ὀρθῷ λόγῳ, ἐσπουδασμένως, ἐρρωμένως, εὐμενῶς, καὶ μηδὲν παρεμπόρευμα, ἀλλὰ τὸν ἑαυτοῦ δαίμονα καθαρὸν ἑστῶτα τηρῇς, ὡσεὶ καὶ ἤδη ἀποδοῦναι δέοι· ἐὰν τοῦτο συνάπτῃς μηδὲν περιμένων μηδὲ φεύγων, ἀλλὰ τῇ παρούσῃ κατὰ φύσιν ἐνεργείᾳ καὶ τῇ ὧν λέγεις καὶ φθέγγῃ ἡρωικῇ ἀληθείᾳ ἀρκούμενος, εὐζωήσεις. ἔστι δὲ οὐδεὶς ὁ τοῦτο κωλῦσαι δυνάμενος.


If. If you act upon the present moment, following a proper plan seriously, steadfastly, and with good intent. If you watch the state of your spirit carefully to conserve its concentration, not allowing yourself to be distracted by any small profit along the way, holding yourself to task as though you were always about to hand your project over to someone else. If you take this in hand without dithering or fleeing, meeting the present moment with no utterance but what rests securely on the nature of your environment and the heroic truth of your own words. Then, you will live well. There is no other person capable of keeping you from this path.