Combinations of Methods.  While any one of the foregoing methods may be used for a single passage it is not usual in actual practice to find one scheme used throughout all the explanatory matter of the speech.  In the first place, the attention of the audience would very likely become wearied by the monotony of such a device.  Certain parts of the material under explanation seem to require one treatment, other portions require different handling.  Therefore good speakers usually combine two or more of these plans.

Partition could hardly be used throughout an entire speech without ruining its interest.  It occurs usually early to map out the general field or scope.  Definition also is likely to be necessary at the beginning of an explanation to start the audience with clear ideas.  It may be resorted to at various times later whenever a new term is introduced with a meaning the audience may not entirely understand.  Both partition and definition are short, so they are combined with other forms.  Examples, likewise, may be introduced anywhere.

The two most frequently closely combined are comparison and contrast.  Each seems to require the other.  Having shown how two things or ideas are alike, the speaker naturally passes on to secure more definiteness by showing that with all their likenesses they are not exactly the same, and that the differences are as essential to a clear comprehension of them as the similarities.  So usual are they that many people accept the two words as meaning almost the same thing, though in essence they are opposites.

The other orders cannot be used in such close combinations but they may be found in varying degrees in many extended speeches of explanation as the nature of the material lends itself to one treatment or another.  A twelve-hundred word discussion of The Future of Food uses examples, contrasted examples, effect to cause, cause to effect (the phrase beginning a paragraph is “there is already evidence that this has resulted in a general lowering “), while the succeeding parts grow in significance until the last is the most important.  A great English statesman in a speech lasting some three hours on a policy of government employed the following different methods at various places where he introduced expository material—­partition (he claimed it was classification, but he listed for consideration only three of the essential five choices), contrast, comparison, time, example, place, cause to effect.  Some of these methods of arranging explanatory matter were used several times.

EXERCISES

1.  Explain a topic by giving three examples.  The class should comment upon their value.

2.  Explain to the class some mechanical operation or device.  The class after listening should decide which method the speaker used.

3.  Explain some principle of government or society following the time order.