_De Divinatione_ takes the form of a suppositious conversation, or better, informal debate, between the author and his brother Quintus. In the first book Quintus, in a rather rambling and leisurely fashion, and with occasional repetition of ideas, upholds divination to the best of his ability, citing many reported instances of successful recourse to it in antiquity. In the second book Tully proceeds, with an air of somewhat patronizing superiority, to pull entirely to pieces the arguments of his brother, who assents with cheerful readiness to their demolition. It is interesting to note that as Pliny’s magic was not his own, so Cicero’s scepticism did not originate wholly with himself. As his other philosophical writings draw their material largely from Greek philosophy, so the second book of the _De Divinatione_ is supposed to have been under considerable obligations to Clitomachus and Panætius.[201] As for the future, the _De Divinatione_ was known in the Middle Ages but its influence seems to have often been scarcely that intended by its author. One of the main points in the argument of Quintus had been his appeal to the past. What race or state, he asked, has not believed in some form of divination? For before the revelation of philosophy, which was discovered recently, public opinion had no doubt of the truth of this art; and after philosophy came forth no philosopher of authority thought otherwise. I have mentioned Pythagoras, Democritus, Socrates. I have left out no one of the ancients save Xenophanes. I have added the Old Academy, the Peripatetics, the Stoics. Epicurus alone dissented.[202] When Tully’s turn to speak came, he rudely disturbed his brother’s reliance upon tradition. “I think it not the part of a philosopher to employ witnesses, who are only haply true, often purposely false and deceiving. He ought to show why a thing is so by arguments and reasons, not by events, especially those I cannot credit.”[203] “Antiquity,” Cicero declared later, “has erred in many respects.”[204] The existence of the art of divination in every age and nation had little effect upon him. There is nothing, he asserted, so widespread as ignorance.[205]