Institutio Oratoria

On the other hand, the accused will always begin by denying the act, since if this can be successfully proved, there is no need to say anything more, while if it is not proved, there remain other means of defence. Similarly, when the dispute turns solely on the act and, the act being proved, there can be no doubt as to the author, arguments may be drawn in like manner both from the person and the facts, although with reference to the question of fact alone.