When a speaker is using a source in his speech, it's because he is looking to enhance the credibility of his speech. If it sounds too good to be true, it's because it probably is. When a speaker want's to take his speech to the next level but doesn't want the audience to think he is plagiarizing; using an outside source is an option the speaker has at his disposal. Also, when a speaker uses a source, he is allowing the audience to track down the information he is providing. The audience can verify if the information being presented is in fact accurate.
A professor at a major University is giving a speech at a graduation ceremony, and he begins his speech by talking about how what kind of challenges young graduates face in life. He goes
A professor at a major University is giving a speech at a graduation ceremony, and he begins his speech by talking about how what kind of challenges young graduates face in life. He goes