27.15, tr. D.A. Russell, in Libanius, Imaginary Speeches: A Selection of Declamations
(London: Duckworth, 1996), p. 127, with endnote on p. 214 (a "morose man" is speaking):
People who say laughter is a specific characteristic of humanity4 are as foolish about this as they are about everything else. It would have been better to regard weeping or crying as our specific characteristic. We all have experiences that deserve this. Laughter, if it is a reaction to good events, is altogether alien to mankind. They have never seen a good thing and never will, only bad things—that is to say, in the first place, one another, and, in the second place, what they do. There is only one day right for laughter, and that is when our good friend Death puts in an appearance.
4. To be capable of laughter is a defining characteristic of a human being, according to some philosophers: cf. Sextus Empiricus, Hypotyposes 2.211; Lucian, Vitarum Auctio 26 (where it is given as a piece of Peripatetic wisdom).
The Greek, from Libanii Opera
, ed. Richard Foerster, Vol. VI: Declamationes XIII-XXX
(Leipzig: B.G. Teubner, 1911), pp. 557-558:
φλυαροῦσιν ὥσπερ καὶ τἄλλα πάντα οἱ τὸ γελᾶν ἴδιον ἀνθρώπου τιθέμενοι. τὸ δακρύειν γὰρ καὶ τὸ οἰμώζειν τίθεσθαι μᾶλλον ἐχρῆν. τούτου γὰρ ἄξια πράττουσιν ἅπαντες. ὁ δὲ γέλως, εἴπερ ἐπὶ χρηστοῖς γίνεται πράγμασιν, ἀλλότριον ἀνθρώπου παντάπασιν. οὐδέποτε γὰρ οὐδὲν χρηστὸν οὔτε εἶδον οὔτε μὴν ὄψονται, ἀλλ' ἀεὶ τὰ κακά, πρῶτον μὲν ἀλλήλους, εἶτα ἃ πράττουσιν. γελᾶν δὲ μίαν ἡμέραν ἐχρῆν, ὅτε ὁ βέλτιστος θάνατος παραγίνεται.