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“A fool laughs even when nothing is funny.”
Γελᾷ δ’ ὁ μωρός, κἄν τι μὴ γέλοιον ᾖ.
Michael Apostolios 3.87
“You are considering ancient history.” A proverb applied to fools and simpletons.
᾿Αρχαϊκὰ φρονεῖς: ἐπὶ τῶν μωρῶν καὶ εὐηθῶν.
Michaelos Apostolios 11.92
“A fool can’t keep quiet”
Μωρὸς σιωπᾷν οὐ δύναται.
“He will blame instead of imitate”: a proverb applied to the uneducable and because it is easier to criticize than emulate.”
Μωμήσεται μᾶλλον ἢ μιμήσεται: ἐπὶ τῶν ἀπαιδεύτων, καὶ ὅτι τὸ ψέγειν τοῦ μιμεῖσθαι ῥᾳότερον.
Also: μωρολογία: properly, “stupid-talking” or “the talk of fools”. But why not: “the science of stupidity”?
A bonus anecdote for this evening;
“Solon, after he was asked by Periander over drink—when the former happened to be quiet—whether he was silent because of a loss of words or foolishness, said “No fool could ever be quiet at a drinking party.”
Σόλων ἐρωτηθεὶς ὑπὸ Περιάνδρου παρὰ πότον, ἐπεὶ σιωπῶν ἐτύγχανε, πότερα διὰ λόγων σπάνιν ἢ διὰ μωρίαν σιωπᾷ, ‘ἀλλ’ οὐδεὶς ἄν’ εἶπε ‘μωρὸς σιωπᾶν ἐν συμποσίῳ δύναιτο’.