Institutio Oratoria

On the other hand if we draw a parallelogram measuring nineteen feet by one, the number of square feet enclosed will be no greater than the number of linear feet making the actual length of the parallelogram, though the perimeter will be exactly as that of the figure which encloses an area of 100 square feet. Consequently the area enclosed by four lines will decrease in proportion as we depart from the form of a square.

It further follows that it is perfectly possible for the space enclosed to be less, though the perimeter be greater. This applies to plane figures only: for even one who is no mathematician can see that, when we have to consider hills or valleys, the extent of ground enclosed is greater than the sky over it.

But geometry soars still higher to the consideration of the system of the universe: for by its calculations it demonstrates the fixed and ordained courses of the stars, and thereby we acquire the knowledge that all things are ruled by order and destiny, a consideration which may at times be of value to an orator.

When

If Nicias had known this when he commanded in Sicily, he would not have shared the terror of his men nor lost the finest army that Athens ever placed in the field. Dion for instance when he came to Syracuse to overthrow the tyranny of Dionysius, was not frightened away by the occurrence of a similar phenomenon. However we are not concerned with the uses of geometry in war and need not dwell upon the fact that Archimedes singlehanded succeeded in appreciably prolonging the resistance of Syracuse when it was besieged.

It will suffice for our purpose that there are a number of problems which it is difficult to solve in any other way, which are as a rule solved by these linear demonstrations, such as the method of division, section to infinity, [*]( Quintilian is perhaps referring to the measurement of the area of an irregular figure by dividing it into a number of small equal and regular figures the size of which was calculable. ) and the ratio of increase in velocity. From this we may conclude that, if as we shall show in the next book an orator has to speak on every kind of subject, he can under no circumstances dispense with a knowledge of geometry.