Plato, Laws 678d

καὶ χαλκὸς καὶ πάντα τὰ μεταλλεῖα συγκεχυμένα ἠφάνιστο, ὥστε ἀπορία πᾶσα ἦν τοῦ ἀνακαθαίρεσθαι τὰ τοιαῦτα, δρυοτομίας τε εἶχον σπάνιν. εἰ γάρ πού τι καὶ περιγεγονὸς ἦν ὄργανον ἐν ὄρεσι, ταῦτα μὲν ταχὺ κατατριβέντα ἠφάνιστο, ἄλλα δὲ οὐκ ἔμελλεν γενήσεσθαι, πρὶν πάλιν ἡ τῶν μεταλλέων ἀφίκοιτο εἰς ἀνθρώπους τέχνη. πῶς γὰρ ἄν; γενεαῖς δὴ πόσαις ὕστερον οἰόμεθα τοῦθʼ οὕτως γεγονέναι;

For iron and bronze and all the metals in the mines had been flooded and had disappeared; so that it was extremely difficult to extract fresh metal; and there was a dearth, in consequence, of felled timber. For even if there happened to be some few tools still left somewhere on the mountains, these were soon worn out, and they could not be replaced by others until men had rediscovered the art of metal-working. They could not. Now, how many generations, do we suppose, had passed before this took place?