Having a good idea or something important to say is not enough. Often how you say something matters as much when it comes to getting your ideas across as the ideas themselves. You need to communicate message to your audience, and do it in such a way that both the message and its importance are received and understood.
Remember that rhetoric is the art of speaking or writing effectively. Therefore, a rhetorical device is a tool that helps you speak or write effectively. There are many rhetorical devices in your toolbox, and we'll discuss a few here.
Have you ever had a line from a song get stuck in your head? You keep hearing the same line over and over again. Often this is because it's sung over and over again in the song. Repetition is the use of any element of language—a sound, word, phrase, clause, or sentence—more than once. Repetition is powerful because it reinforces an idea. It also makes the audience remember it, sometimes months or years later!