From what I understand, rhetoric is an idea that you are able to express to others regardless of the medium; be it written, spoken, illustrated, acted or any other form of expression.  Based on this definition, a rhetorician is anyone that has expressed or is expressing an idea that may be interpreted by an audience.  Many people, including myself at some points, get confused between rhetoric and literature or discourse.

The difference between rhetoric and literature or discourse is essentially the same as the difference between a dog and a golden retriever or yellow lab respectively. By this I mean that the three styles have their own definition, but can be linked together. While literature is an idea that has been written, discourse is an idea that can be either written or spoken and both of these are parts that make up the heading of rhetoric. As a result of literature and discourse being sub-categories of rhetoric, just because something classifies as rhetoric, does not necessarily mean that the given idea is either literature or discourse.  They  are parts of rhetoric in the same way as golden retrievers and yellow labs are parts of the species of dog; they are both obviously dogs but just seeing dog does not automatically make it a golden retriever or yellow lab.

To say that you were moved by a piece of rhetoric is a very open statement.  While what you witnessed may have very well been literature or discourse, it could have been a film or a photograph.  By simply calling it rhetoric, your audience will not be able to fully understand.