or a common topic either contains some
amplification of a well understood thing,--as if any one were desirous
to show that a man who has murdered his father is worthy of the very
extremity of punishment; and this topic is not to be used except when
the cause has been proved and is being summed up;--or of a doubtful
matter which has some probable arguments which can be produced on the
other side of the question also; as a man may say that it is right to
put confidence in suspicions, and, on the contrary, that it is not
right to put confidence in suspicions. And a portion of the common
topics is employed in indignation or in complaint, concerning which we
have spoken already. A part is used in urging any probable reason on
either side.

But an oration is chiefly distinguished and made plain by a sparing
introduction of common topics, and by giving the hearers actual
information by some topics, and by confirming previously used
arguments in the same way. For it is allowable to say something common
when any topic peculiar to the cause is introduced with care; and when
the mind of the hearer is refreshed so as to be inclined to attend to
what follows, or is reawakened by everything which has been already
said. For all the embellishments of elocution, in which there is a
great deal both of sweetness and gravity, and all things, too, which
have any dignity in the invention of words or sentences, are bestowed
upon common topics.

Wherefore there are not as many common topics for orators as there are
for lawyers. For they cannot be handled with elegance and weight, as
their nature requires, except by those who have acquired a great flow
of words and ideas by constant practice. And this is enough for us to
say in a general way concerning the entire class of common topics.

XVI. Now we will proceed to explain what common topics are usually
available in a conjectural statement of a case. As for instance--that
it is proper to place confidence in suspicions, or that it is not
proper, that it is proper to believe witnesses, or that it is not
proper, that it is proper to believe examinations, or that it is not
proper, that it is proper to pay attention to the previous course of a
man's life, or that it is not proper, that it is quite natural that a
man who has done so and so should have committed this crime also, or
that it is not natural, that it is especially necessary to consider
the motive, or that it is not necessary. And all t