55.  The Power of Persuading.  Finally, we have to consider the question of how an argument can be made persuasive—­probably the most difficult subject in the range of rhetoric on which to give practical advice.  The key to the whole matter lies in remembering that we are here dealing with feelings, and that feelings are irrational and are the product of personal experience.  The experience may be bitter or sweet, and to some degree its effects are modified by education; but in substance your feelings and emotions make you what you are, and your capacities in these directions were born with you.  If the citizens of a town have no feeling about political dishonesty, reformers may talk their throats out without producing any result; it is only when taxes get intolerable or the sewers smell to heaven that anything will be done.  Many people die for whose deaths each of us ought to feel grief, but if these people have never happened to touch our feelings, we can reason with ourselves in vain that we should feel deeply grieved.  Feeling and emotion are the deepest, most primitive part of human nature; and very little of its field has been reduced to the generalizations of reason.[59]

When you come, therefore, in the making of your argument to the point of stirring up the feelings of your readers on the subject, do not waste any time in considering what they ought to feel:  the only pertinent question is what they do feel.  On your shrewdness in estimating what these feelings are, and how strong they are, will hang your success as an advocate.  Tact is the faculty you need now—­the faculty of judging men, of knowing when they will rise to an appeal, and when they will lie back inert and uninterested.  This is a matter you cannot reason about; if you have the faculty it will be borne in on you how other men will feel on your subject.  The skill of politicians, where it does not confine itself to estimating how much the people will stand before rebelling, consists in this intuition of the movement of public opinion; and the great leaders are the men who have so sure a sense of these large waves of popular feeling that they can utter at the right moment the word that will gather together this diffused and uncrystallized feeling into a living force.  Lincoln’s declaration, “A house divided against itself cannot stand, I believe that this government cannot endure permanently half slave and half free,” brought to a head a conflict that had been smoldering ever since the adoption of the Constitution, and made him the inevitable leader who was to bring it to a close.  It will be noticed, however, that the time had to come before the inspired word could make its appeal.  The abolitionists and antislavery men had long been preaching the same doctrine that Lincoln uttered, and the folly and wickedness of slavery had been proved by philosophers and preachers for generations.  Until the time grows ripe the most reasonable doctrine does not touch the hearts of men; when the time has ripened, the leader knows it and speaks the word that sets the world on fire for righteousness.