No human being will ever know the truth, for even if they happened to say it by chance, they would not know they had done so.

καὶ τὸ μὲν οὖν σαφὲς οὔτις ἀνὴρ γένετ᾿ οὐδέ τις ἔσται εἰδὼς ἀμφὶ θεῶν τε καὶ ἅσσα λέγω περὶ πάντων· εἰ γὰρ καὶ τὰ μάλιστα τύχοι τετελεσμένον εἰπών, αὐτὸς ὅμως οὐκ οἶδε· δόκος δ᾿ ἐπὶ πᾶσι τέτυκται. | And thus there has never been any man, nor will there ever be one, Who knows what is clear about the gods and whatever I say about all things. For even if he happened most to say something perfect, He himself nonetheless does not know: opinion is set upon all things. (tr. A. Laks, G. W. Most, 2016)