Plutarch Septem sapientium convivium 17

[17] While Solon was still speaking, Gorgus, Periander’s brother, came in; for it happened that, in consequence of certain oracles, he had been sent to Taenarum, in charge of a sacred mission to offer due sacrifice to Poseidon. After we had greeted him, and Periander had embraced and kissed him, Gorgus sat down beside his brother on the couch, and gave him a report intended apparently for him alone, and he, as he listened, seemed much affected at the story; for he appeared in some ways troubled, in some ways indignant, and oftentimes incredulous, and then again amazed. Finally with a laugh he said to us, In the circumstances I should like to tell the news which I have just heard, but I hesitate, since I heard Thales say once that what is probable one should tell, but what is impossible one should shroud in silence.

Thereupon Bias, interrupting, said, But Thales is responsible also for this sage remark, that one should not believe enemies even about things believable, and should believe friends even about things unbelievable; the name enemies he assigned, I think, to the wicked and foolish, and friends to the good and sensible. And so, Gorgus, he continued, it should be told to all, or rather, to compete with those newly invented dithyrambs, ¹ there should be heard the stronger notes of the story which your arrival has brought to us.

[17] And before Solon had fully finished, in came Gorgias, Periander’s brother, who was just returned from Tacnarum, whither he had been sent by the advice of the oracle to sacrifice to Neptune and to conduct a deputation. Upon his entrance we welcomed him home; and Periander having among the rest saluted him, Gorgias sat by him upon a bed, and privately whispered something to his brother which we could not hear. Periander by his various gestures and motions discovered different affections; sometimes he seemed sad and melancholic, by and by disturbed and angry; frequently he looked as doubtful and distrustful men use to do; awhile after he lifts up his eyes as is usual with men in a maze. At last recovering himself, saith he, I have a mind to impart to you the contents of this embassy; but I scarce dare do it, remembering Thales’s aphorism, how things impossible or incredible are to be concealed and only things credible and probable are to be related. Bias answered, I crave leave to explain Thales’s saying, We may distrust enemies, even though they speak things credible, and trust friends, even though they relate things incredible; and I suppose by enemies he meant vicious men and foolish, and by friends, wise and good men. Then, brother Gorgias, quoth Periander, I pray relate the whole story particularly.