The impact that speeches and presentations can have on an audience can be well seen in their direct willingness to donate, because everyone always wants to have full control over what is in their wallet. Mark Twain once explained this in a very clear way:

“A missionary who had a splendid voice preached. With movingly simple words he told of the sufferings of the natives. I was so moved that instead of the 50 cents I was thinking of offering, I doubled the donation. The missionary’s descriptions became more and more forceful, and I resolved to increase my gift further: to two, three, five dollars. Finally, I was close to crying. I found all the money I was carrying wasn’t enough, and I fumbled for my checkbook.”

Now, however, the preacher made a crucial mistake, which caused him to gamble away the capital his listener was about to invest: “The missionary talked and talked, and I gradually got bored with the whole thing. I dropped the checkbook idea and went back down to five dollars. The missionary kept talking. I thought, ‘One dollar will do!’ The missionary still couldn’t find an ending When he finally finished, I put ten cents on the plate.”