Institutio Oratoria

This type of oratory seems to me to offer a more varied field for eloquence, since both those who ask for advice and the answers given to them may easily present the greatest diversity. Consequently there are three points which must be specially borne in mind in advice or dissuasion: first the nature of the subject under discussion, secondly the nature of those who are engaged in the discussion, and thirdly the nature of the speaker who offers them advice.

As to the subject under discussion its practicability is either certain or uncertain. In the latter case this will be the chief, if not the only point for consideration; for it will often happen that we shall assert first that something ought not to be done, even if it can be done, and secondly, that it cannot be done. Now when the question turns on such points as to whether the Isthmus can be cut through, the Pontine Marshes drained, or a harbour constructed at Ostia, or whether Alexander is likely to find land beyond the Ocean, [*]( the theme of a suasoria of the elder Seneca ( Suas. i.). Alexander deliberates whether to sail forth into the ocean. ) we make use of conjecture.

But even in connection with things that are undoubtedly feasible, there may at times be room for conjecture, as for instance in questions such as whether Rome is ever likely to