Cicero, De Finibus
1.8.27-28 (tr. H. Rackham):
"You must not find fault with members of opposing schools for criticizing each other's opinions; though
I always feel that insult and abuse, or ill-tempered
wrangling and bitter, obstinate controversy are
beneath the dignity of philosophy."
"I am quite of
your mind,” said Torquatus; "it is impossible to debate without criticizing, but it is equally impossible to debate properly with ill-temper or obstinacy."
"quamobrem dissentientium inter se reprehensiones
non sunt vituperandae; maledicta, contumeliae, tum
iracundae contentiones concertationesque in disputando pertinaces indignae philosophia mihi videri
tum Torquatus: "prorsus," inquit, "assentior;
neque enim disputari sine reprehensione, nec cum
iracundia aut pertinacia recte disputari potest."