Passage 9.31.7
ἐπὶ δὲ ἄκρᾳ τῇ κορυφῇ τοῦ Ἑλικῶνος ποταμὸς οὐ μέγας ἐστὶν ὁ Λάμος. Θεσπιέων δὲ ἐν τῇ γῇ ἡ Δονακών ἐστιν ὀνομαζόμενος· ἐνταῦθά ἐστι Ναρκίσσου πηγή, καὶ τὸν Νάρκισσον ἰδεῖν ἐς τοῦτο τὸ ὕδωρ φασίν, οὐ συνέντα δὲ ὅτι ἑώρα σκιὰν τὴν ἑαυτοῦ λαθεῖν τε αὐτὸν ἐρασθέντα αὑτοῦ καὶ ὑπὸ τοῦ ἔρωτος ἐπὶ τῇ πηγῇ οἱ συμβῆναι τὴν τελευτήν. τοῦτο μὲν δὴ παντάπασιν εὔηθες, ἡλικίας ἤδη τινὰ ἐς τοσοῦτο ἥκοντα ὡς ὑπὸ ἔρωτος ἁλίσκεσθαι μηδὲ ὁποῖόν τι ἄνθρωπος καὶ ὁποῖόν τι ἀνθρώπου σκιὰ διαγνῶναι·
On the very peak of Mount Helicon, the river Lamos flows, which is not large. In the territory of Thespiae is a place called Donakon. Here is located the spring of Narcissus. It is said that Narcissus gazed into this water, and not understanding that he saw merely his own reflection, he unwittingly fell in love with himself, and due to this passion he met his end at the spring. This entire account seems altogether foolish, that one should reach such an age at which love could affect a person, yet still be unable to distinguish between a human being and a mere human shadow.