Advertising is fundamentally persuasion, and persuasion happens to be not a science, but an art.
This quote from Bill Bernbach highlights a core belief of rhetoric, which is the "the art of discourse" or the study of how to write, speak, and communicate in a persuasive, informative, and inspiring way. It is using linguistic techniques to influence behavior and emotions -- an essential skill in the marketing industry.
Rhetoric can also be a helpful tool for inspiring creative ideas. Curtis Newbold created this infographic highlighting 10 concepts used by ancient philosophers to master the art of persuasion.