Passage 10.23.7
καὶ οἱ μὲν ἐστρατοπεδεύσαντο ἔνθα νὺξ κατελάμβανεν ἀναχωροῦντας, ἐν δὲ τῇ νυκτὶ φόβος σφίσιν ἐμπίπτει Πανικός· τὰ γὰρ ἀπὸ αἰτίας οὐδεμιᾶς δείματα ἐκ τούτου φασὶ γίνεσθαι. ἐνέπεσε μὲν ἐς τὸ στράτευμα ἡ ταραχὴ περὶ βαθεῖαν τὴν ἑσπέραν, καὶ ὀλίγοι τὸ κατʼ ἀρχὰς ἐγένοντο οἱ παραχθέντες ἐκ τοῦ νοῦ, ἐδόξαζόν τε οὗτοι κτύπου τε ἐπελαυνομένων ἵππων καὶ ἐφόδου πολεμίων αἰσθάνεσθαι · μετὰ δὲ οὐ πολὺ καὶ ἐς ἅπαντας διέδρα ἡ ἄγνοια.
And so they encamped wherever night overtook them during their retreat. But during the night, a panic terror seized upon them—for fears that occur without any rational cause are said to be due to Pan. Disorder struck the army around late evening; at first only a few men lost their senses, imagining that they heard the sounds of galloping horses and perceived the approach of enemies. Soon enough, however, the confusion spread among the entire army.