Cicero summoned as a witness in a certain case Castus Popillius, who wanted to be a lawyer, but was ignorant and stupid. When he denied knowing anything, Cicero said, ‘Very likely you think you are being asked about some point of law !’ 1
1 Cf. Plutarch's Life of Cicero, chap. xxvi. (874 A), where the name of the man is given as Publius Consta.