Aeneas Silvius Piccolomini, de liberorum educatione XXXVIII:
“Baseness should be absent from every speech, since – as Democritus says – speech is the shadow of action; the Apostle says ‘bad conversations corrupt good morals,’ – a saying which Jerome asserts to have been taken from Menander. Since many cheerful conversations conceal some bit of hidden evil (just as poisons are drunk mixed with honey), we should when exposed to base speech imitate Ulysses, who put wax in his ears to avoid hearing the songs of the Sirens. There should be an easiness in conversation, pleasantry in addressing those we meet, and kindness in our responses, for grave habits of conversation draw deserved hatred upon them. Stubbornness should be excluded from your disputes; prudence should prevail, and reason should win the day. It is a fine thing not only to win, but also to know when you are beaten. One must hold in mind the opinion of Euripides, who claims that when two people are conversing, and one of them is mad, he is by far the wiser who reins in his words.”
NOTE: The Euripides bit is quoted at Plutarch, de liberis educandis 14:
“When two are speaking and one is mad,
the one who does not contend with words is the wiser.”
δυοῖν λεγόντοιν, θατέρου θυμουμένου,
ὁ μὴ ἀντιτείνων τοῖς λόγοις σοφώτερος
Absit autem in omni sermone turpitudo, quoniam actionis umbra, ut ait Democritus, extat oratio, ‘corrumpunt bonos mores,’ ut Apostolus ait, ‘confabulationes malae,’ quod ex Menandro receptum Hieronymus astruit. Et quoniam plerumque sermones qui festivitatem habent, latenter aliquid admittunt mali, ut venena melle permixta bibantur, in omni turpiloquio est imitandus Ulixes, qui ceras affixit auribus, ne Sirenarum cantus exaudiret. Adsit in colloquendo facilitas, in obvios compellando suavitas, in respondendo benignitas, nam graves in collocutionibus mores digna in se odia contrahunt. Absit in contentionibus pertinacia, vincat prudentia, obtineant rationes; non solum vincere sed etiam scire vinci speciosum est. Tenenda est Euripidis sententia, qui, duobus obloquentibus cum alter furit, eum longe sapientiorem affirmat, qui verba frenit.