Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
it is not immediately obvious what it is. And when we have decided what it is, there remains the question of its quality. These three points once ascertained, there is no further question to ask. These heads cover both definite and indefinite questions. One or more of them is discussed in every demonstrative, deliberative or forensic theme.
These heads again cover all cases in the courts, whether we regard them from the point of view of rational or legal questions. For no legal problem can be settled save by the aid of definition, quality and conjecture.
Those, however, who are engaged in instructing the ignorant will find it useful at first to adopt a slightly less rigid method: the road will not be absolutely straight to begin with, but it will be more open and will provide easier going. I would have them therefore learn above all things
Hence arise those questions of legal action or competence. For there are some things, which, although not laudable in themselves, are yet permitted by law; witness the passage in the Twelve Tables authorising creditors to divide up a debtor's body amongst themselves, a law which is repudiated by public custom. There are also certain things which although equitable are prohibited by law; witness the restrictions placed on testamentary disposition. [*]( e.g. that the legal heir must receive at least a quarter of the property. )
The accuser likewise has four things which he must keep in mind: he must prove that something was done, that a particular act was done, that it was wrongly done, and that he brings his charge according to law. Thus every cause will turn on the same sorts of questions, though the parts of plaintiff and defendant will sometimes be interchanged: for instance in the case of a claim for a reward, it will be the plaintiffs task to show that what was done was right.