Institutio Oratoria

is not wholly unreasonable. Still no one should interpret it to mean that you must stop short of nothing. For the Greeks are right when they lay it down as a rule that we should not attempt the impossible. But whenever the double-barrelled defence of which I am speaking is employed, we must aim at making the first argument support the credibility of the second. For he who might without danger to himself have confessed to the commission of the act, can have no motive for lying when he denies the commission.