Book 7
2.1
III. Conjecture is followed by definition. For the man who cannot assert that he has done nothing, must needs take refuge in the assertion that lie has not committed the act which is alleged against him. Consequently the laws which govern definition are for the most part the same as those which govern conjecture, the only difference lying in the method to be employed in defence in cases such as those concerned with theft, deposits or adultery. For just as we say, I have not committed theft, I never received a deposit, I am not guilty of adultery, so we say, This is not theft, this is not a deposit, this is not adultery.
2.2
Sometimes we may pass from quality to definition, as in actions concerned with lunacy, cruelty and offences against the State. In such cases if it is impossible to assert that the acts alleged were right, we are left with such pleas as, To use bad language to one's wife does not amount to cruelty. Definition is the statement of the fact called in question in appropriate, clear and concise language.
2.3
As I have already said, V. x. 55. it consists mainly in the statement of genus, species, difference and property. For example, if you wish to define a horse (for I will take a familiar example), the genus is animal, the species mortal, the diffrence irrational (since man also is mortal) and the properly neighing. Definition is employed by the orator for a number of different reasons.
