Institutio Oratoria

I am aware that some writers have shown pedantic zeal in making a minute classification of similes, and have pointed out that there is lesser similitude (such as that of a monkey to a man or a statue when first blocked out to its original), a greater similitude (for which compare the proverb

As like as egg to egg

), a similitude in things dissimilar (an elephant, for instance, and an ant both belong to the genus animal ),and dissimilitude in things similar (puppies and kids, for example, are unlike the parents, [*](Verg. Ecl i. 23. ) for they differ from them in point of age).

So too they distinguish between contraries: some are opposites, as night to day, some hurtful, as cold water to a fever, some contradictory, as truth to falsehood, and some negative, as things which are not hard when contrasted with things which are hard. But I cannot see that such distinctions have any real bearing on the subject under discussion.

It is more important for our purpose to note that arguments may be drawn from similar, opposite, and dissimilar points of law. As an example of the first, take the following passage from the Topica of Cicero, [*](iii. 15.) where he argues that a man to whom the usufruct of a house has been left will not restore it in the interests of the heir if it collapses; just as lie would not replace a slave if he should die. The following will provide an example of an argument drawn from opposite points of law:

The absence of a formal contract is no bar to the legality of a marriage, provided the parties cohabit by mutual consent, since the signing of a formal document will count for nothing in the absence of such mutual consent.

An instance of an argument drawn from dissimilar points of law occurs in the pro Caecina of Cicero [*](xii. 34.) :

If anyone had driven me from my house by armed violence, I should have ground for action against him. Have I then no ground, if he has prevented me from entering my house?

Dissimilar points may be illustrated by the following example [*](cp. Cic. Top. iii. 13 and 16. ) :

Because a man has bequeathed all his silver to a given person and this bequest is regarded as including silver coin as well as plate, it does not follow that he intended all outstanding debts to be paid to the legatee.