Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
There are special rules which must be observed both by speakers and writers. Language is based on reason, antiquity, authority and usage. Reason finds its chief support in analogy and sometimes in etymology. As for antiquity, it is commended to us by the possession of a certain majesty, I might almost say sanctity.
Authority as a rule we derive from orators and historians. For poets, owing to the necessities of metre, are allowed a certain licence except in cases where they deliberately choose one of two expressions, when both are metrically possible, as for instance in imo de stirpe recisum and aeriae quo congessere palumbes or silice in nuda [*](Aen. xii. 208: cutaway from the lowest root. Ecl. iii. 69: where airy doves have made their nest. Ecl. i. 15: on the naked rock. Stirps, palumbes and silex are usually masculine. ) and the like. The judgment of a supreme orator is placed on the same level as reason, and even error brings no disgrace, if it result from treading in the footsteps of such distinguished guides.
Usage however is the surest pilot in speaking, and we should treat language as currency minted with the public stamp. But in all these cases we have need of a critical judgment, especially as regards analogy (a Greek term for which a Latin equivalent has been found in proportion).
The essence of analogy is the testing of all subjects of doubt by the application of some standard of comparison about which there is no question, the proof that is to say of the uncertain by reference to the certain. This can be done in two different ways: by comparing similar words, paying special attention to their final syllables
Comparison of nouns will reveal either their gender or their declension: in the first case, supposing the question is raised as to whether junis be masculine or feminine, panis will supply a standard of comparison: in the second case, supposing we are in doubt as to whether we should say hac domu or hac domo, domuum or domorum, the standard of comparison will be found in words such as anus or manus.