If you would understand what a scientific demonstration of an article or proposition is like, it would pay you to listen to the demonstration by a well-trained salesman of the National Cash Register Company. This company drills its salesmen thoroughly in this part of their work, until they have every detail fastened in their minds in its proper logical order. An old salesman of this company should be able to repeat his formula backwards as well as in the regular order--beginning at the middle and working either backward or forward, at will. He understands the "why" and "what for" of every detail of his article and proposition, and is taught to present them in their logical order. Listening to a talk of one of their best salesmen is a liberal education in demonstration. The essence of this stage of the demonstration is that it should be given in the spirit of a conversational recital of an interesting story, or description of an event. Speak in an impersonal way; that is, avoid suggesting to the prospect that you are trying to sell him the thing. Let this part of your talk be given from the sheer enthusiasm inspired in your mind by the merits of your proposition. Let it be a labor of love--forget all about your hope of sale or profit. Your one aim and object of life, at that moment, should be that of inspiring the prospect with the wonderful merits of your proposition, which you yourself entertain. Yours should be the spirit of the propogandist seeking converts--imparting information for the good of others, and "for the cause." Forget the forthcoming collection plate, in the earnestness of your sermon.