Gorgias of Leontini, Encomium of Helen

αἱ γὰρ ἔνθεοι διὰ λόγων ἐπῳδαὶ ἐπαγωγοὶ ἡδονῆς, ἀπαγωγοὶ λύπης γίγνονται· συγγιγνομένη γὰρ τῇ δόξῃ τῆς ψυχῆς ἡ δύναμις τῆς ἐπῳδῆς ἔθελξε καὶ ἔπεισε καὶ μετέστησεν αὐτὴν γοητείᾳ. γοητείας δὲ καὶ μαγείας δισσαὶ τέχναι ηὕρηνται, αἵ εἰσι ψυχῆς ἁμαρτήματα καὶ δόξης ἀπατήματα.

For inspired incantations through words become bringers of pleasure and removers of grief; for the power of the incantation, mingling with the opinion of the soul, beguiles it and persuades it and changes it by witchcraft. Of witchcraft and magic two arts have been discovered, which are errors of the soul and deceptions of opinion.

τὸν αὐτὸν δὲ λόγον ἔχει ἥ τε τοῦ λόγου δύναμις πρὸς τὴν τῆς ψυχῆς τάξιν ἥ τε τῶν φαρμάκων τάξις πρὸς τὴν τῶν σωμάτων φύσιν. ὥσπερ γὰρ τῶν φαρμάκων ἄλλους ἄλλα χυμοὺς ἐκ τοῦ σώματος ἐξάγει, καὶ τὰ μὲν νόσου τὰ δὲ βίου παύει, οὕτω καὶ τῶν λόγων οἱ μὲν ἐλύπησαν, οἱ δὲ ἔτερψαν, οἱ δὲ ἐφόβησαν, οἱ δὲ εἰς θάρσος κατέστησαν τοὺς ἀκούοντας, οἱ δὲ πειθοῖ τινι κακῇ τὴν ψυχὴν ἐφαρμάκευσαν καὶ ἐξεγοήτευσαν.

The power of speech stands in the same relation to the ordering of the soul as the ordering of drugs to the nature of bodies. For just as different drugs draw different humours out of the body, and some put an end to disease, others to life, so too among speeches some cause grief, others delight, others fear, others put their hearers in a bold frame of mind, and others drug and bewitch the soul with some evil persuasion.