Institutio Oratoria

But for the fact that Cicero [*](Top. iii. 12. ) has done so, I should regard it as absurd to add to these what is styled the conjugate argument, such as

Those who perform a just act, act justly,

Every man has a common right to send his cattle to graze in a common pasture.

Some call these arguments derived from causes or efficients by the Greek name ἐκβάσεις that is, results; for in such cases the only point considered is how one thing results from another. Those arguments which prove the lesser from the greater or the greater from the less or equals from equals are styled apposite or comparative.

A conjecture as to a fact is confirmed by argument from something greater in the following sentence:

If a man commit sacrilege, he will also commit theft

He who lies easily and openly will commit perjury

He who has taken a bribe to give a false verdict will take a bribe to give false witness.

Points of law may be proved in a similar manner; from something greater, as in the sentence

If it is lawful to kill an adulterer, it is lawful to scourge him

If it is lawful to kill a man attempting theft by night, how much more lawful is it to kill one who attempts robbery with violence

The penalty which is just in the case of parricide is also just in the case of matricide.