Quintilian Institutio Oratoria 5.13.49

[49] Sometimes however it may be possible to put forward something not unlike such objections, if some point included by our opponent in the depositions which he produces has been discussed among his advocates ¹ : for then we shall be replying to something which they have said and not to an objection which has been invented by ourselves; or again, this will be possible if the case is of such a nature that we are in a position to state certain definite objections which are absolutely essential to our opponent's case: for instance, if stolen goods have been discovered in a house, the accused must of necessity allege either that they were brought there without his knowledge or deposited with him or given to him and we may therefore answer all these points even although they have not been put forward.