The etymology of happiness. The first sentence is an etymological thesis: TERMεὐδαιμονία is literally taken apart into εὖ + TERMδαίμων — "the good state of one's daimon." Happiness is not a sum of circumstances but the condition of the inner divinity: that TERMδαίμων which "Zeus gave to each as guardian" and which is each person's mind (5.27; cf. 2.13, 2.17, 3.16). Whoever keeps his daimon good is happy by the very definition of the word; the external simply has no place in the formula.

The text. The manuscripts' «δαίμων ἀγαθὸς ἢ ἀγαθόν» is faulty; our source prints the editorial supplement ‹δαιμόνιον› ("…or a good divinity"). Long translates the bare ἀγαθόν ("or a good thing"), while the edition Rogovin worked from read ἡγεμονικὸν ἀγαθόν — hence his "or such a ruling part." Doctrinally all three branches converge: the good daimon, the good divinity within, and the good ruling part are one and the same identification of the inner god with the ἡγεμονικόν (cf. 5.27: "the daimon is each person's mind").

The expulsion of the impression. The second half is a small drama: a sudden turn to the uninvited guest. "What are you doing here, TERMimpression?" — a polite exorcism without anger: "EXERCISEgo away, by the gods, the way you came… I am not angry with you — only go" (μόνον ἄπιθι). The psychology is exact: anger at the impression would itself be a second impression taken seriously; the doorkeeper (EXERCISEπροσοχή) shows it out without joining battle. ἐλήλυθας κατὰ τὸ ἀρχαῖον ἔθος — "you have come by old habit": impressions travel the worn paths of habituation, and their arrival is not in our power — what is in our power is not to detain them (cf. 5.2 — "how easy to push away the troubling impression"; 7.29 — "wipe out the impression"; 8.29). The neighbourhood of the etymology is no accident: the daimon's goodness just is the cleanliness of the anteroom where uninvited guests are not entertained. The governing discipline is assent; the sustaining one, desire.