Public speeches are delivered on many different occasions, but no matter what the occasion, the speaker hopes to get the audience to accept his point of view.This purpose should be put into a sentence which is specific and concrete. A clear knowledge of the purpose in speaking is as helpful to the speaker as a road map is to the driver. The purpose gives direction to the speech and, to a degree, governs all subsequent efforts the speaker makes.Having one central idea, broken up into sub-ideas properly selected and supported, is a means of insuring unity in a speech. As a result of this unity, the audience will believe that you have given it a complete picture.In order to do this, it must get the attention of the audience, make the audience like or respect you (or both), and create an interest in the ideas you are going to present.