Plutarch De Garrulitate 15

[15] Now if anyone were to ask, no one would pass the traitor by and name anyone else. So Euthycrates ² roofed his house with the timber he got from Macedon, ³ as Demosthenes ⁴ says, and Philocrates ⁵ received much money and bought strumpets and fish; and to Euphorbus and Philagrus, who betrayed Eretria, the king ⁶ gave land. But the babbler is a traitor who volunteers his services without pay: he does not betray horses ⁷ or city-walls, but divulges secrets connected with lawsuits, party strife, and political manoeuvres. No one thanks him, but he himself, if he can win a hearing, must owe thanks. The result is that the verse directed at the man who recklessly and injudiciously pours forth and squanders his own possessions, fits the foolish talker also: You are no friend or well-wisher in revealing this: it’s your disease, you love to be babbling and prating.

[15] Now then if the question should be asked, Which are the worst and most pernicious sort of people? I do not believe there is any man that would omit to name a traitor. By treason it was that Euthycrates covered the uppermost story of his house with Macedonian timber, according to the report of Demosthenes; that Philocrates, having received a good sum of money, spent it upon whores and fish; and that Euphorbus and Philagrus, who betrayed Eretria, were so well rewarded by the king with ample Possessions. But a prattler is a sort of traitor that no man needs to hire, for that he offers himself officiously and of his own accord. Nor does he betray to the enemy either horse or walls; but whatever he knows of public or private concerns requiring the greatest secrecy, that he discloses, whether it be in courts of judicature, in conspiracies, or management of state affairs, ’tis all one; he expects not so much as the reward of being thanked for his pains; nay, rather he will return thanks to them that give him audience. And therefore what was said upon a certain spendthrift that rashly and without any discretion wasted his own estate by his lavish prodigality to others, may well be retorted upon a common prattler: