Book 1
3.7
From what has been said it is evident that the orator must first have in readiness the propositions on these three subjects.The expedient, the just, the honorable, and their contraries. Now, necessary signs, probabilities, and signs are the propositions of the rhetorician; for the syllogism universallyὅλως: or, reading ὅλος, the syllogism as a whole. consists of propositions, and the enthymeme is a syllogism composed of the propositions above mentioned.
3.8
Again, since what is impossible can neither have been done nor will be done, but only what is possible, and since what has not taken place nor will take place can neither have been done nor will be done, it is necessary for each of the three kinds of orators to have in readiness propositions dealing with the possible and the impossible, and as to whether anything has taken place or will take place, or not.
