καὶ τὸ σιγᾶν πολλάκις ἐστὶ σοφώτατον ἀνθρώπῳ νοῆσαι → and silence is often the wisest thing for a man to heed, and often is man's best wisdom to be silent, and often keeping silent is the wisest thing for a man to heed
Use copper, iron, silver, gold, etc.
metals: P. μεταλλεῖα, τά (Plato, Leges 678D; cf., Plato, Critias, 114E).
molten metal: V. μύδρος, ὁ.