Institutio Oratoria

Quintilian

Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.

As regards geometry, [*](Geometry here includes all mathematics.) it is granted that portions of this science are of value for the instruction of children: for admittedly it exercises their minds, sharpens their wits and generates quickness of perception. But it is considered that the value of geometry resides in the process of learning, and not as with other sciences in the knowledge thus acquired. Such is the general opinion.

But it is not without good reason that some of the greatest men have devoted special attention to this science. Geometry has two divisions; one is concerned with numbers, the other with figures. Now knowledge of the former is a necessity not merely to the orator, but to any one who has had even an elementary education. Such knowledge is frequently required in actual cases, in which a speaker is regarded as deficient in education, I will not say if he hesitates in making a calculation, but even if he contradicts the calculation which he states in words by making an uncertain or inappropriate gesture with his fingers. [*]( There was a separate symbol for each number, depending on the hand used and the position of the fingers. See Class. Review, 1911, p. 72 ) Again linear geometry is frequently required in cases, as in lawsuits about boundaries and measurements.

But geometry and oratory are related in a yet more important way than this.

In the first place logical development is one of the necessities of geometry. And is it not equally a necessity for oratory? Geometry arrives at its conclusions from definite premises, and by arguing from what is certain proves what was previously uncertain. Is not this just what we do in speaking? Again are not the problems of geometry almost entirely solved by the

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syllogistic method, a fact which makes the majority assert that geometry bears a closer resemblance to logic than to rhetoric? But even the orator will sometimes, though rarely, prove his point by formal logic.

For, if necessary, he will use the syllogism, and he will certainly make use of the enthymeme which is a rhetorical form of syllogism. [*]( See v. xiv. I for an example from the Pro Ligario. The cause was then doubtful, as there were arguments on both sides. Now, however, we must regard that cause as the better, to which the gods have given their approval. ) Further the most absolute form of proof is that which is generally known as linear demonstration. And what is the aim of oratory if not proof?