Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
On the other hand in the case of a witness who is reluctant to tell the truth, the essential for successful examination is to extort the truth against his will This can only be done by putting questions which have all the appearance of irrelevance. If this he done, he will give replies which he
For just as in a set speech we usually collect detached arguments which in themselves seem innocuous to the accused, but taken together prove the case against him, so we must ask the reluctant witness a number of questions relative to acts antecedent or subsequent to the case, places, dates, persons, etcetera, with a view to luring him into some reply which will force him to make the admissions which we desire or to contradict his previous evidence.