Enchiridion · §18

ὁ κόραξ ἐὰν κράξας οἰωνίσηται κακόν, μὴ συναρπαζέσθω σε ἡ φαντασία, ἀλλ᾽ εὐθὺς διαστέλλε παρὰ σεαυτῷ καὶ λέγε ὅτι "ἐμοὶ τούτων οὐδὲν ἐπισημαίνεται, ἀλλ᾽ ἢ τῷ σωματίῳ μου ἢ τῷ κτησειδίῳ μου ἢ τῇ δόξῃ μου ἢ τοῖς τέκνοις ἢ τῇ γυναικί. ἐμοὶ δὲ πάντα εὐοίωνα ἐάν τε βούλωμαι".

ho korax ean kraxas oiōnisētai kakon, mē sunarpazesthō se hē phantasia, all' euthus diastelle para seautō kai lege hoti 'emoi toutōn ouden episēmainetai, all' ē tō sōmatiō mou ē tō ktēseidiō mou ē tē doxē mou ē tois teknois ē tē gunaiki. emoi de panta euoiōna ean te boulōmai'.

If a raven croaks an omen of bad luck, do not let the impression carry you away. Instead, draw a distinction immediately within yourself and say: 'None of these signs say anything about me — they concern only my body, my property, my reputation, my children, my wife. For me, every sign is auspicious, if I choose to make it so.'

— Enchiridion 18

Source: Greek (Schenkl/Oldfather critical edition tradition) + Long 1877 English translation