This can be done by direct action - force, threats, bribes, for example - or it can be done by the use of "signs", of which the most important are words in speech or writing" (Kennedy, 3)
As we may notice, this definition doesn't exclude the possibility of using other types of signs than those commonly used, the linguistic signs. On the contrary, it implies the fact that rhetoric uses more than a system of signs. Newer approaches on rhetoric, as well as the broader definition of rhetoric as "the totality of connotators" (Barthes, 38) - connotators being the signifiers of connotation that correspond to the general ideology - place the image at the centre of a system of signs. Image is seen as able of conveying meaning and expressing ideas as well as having a persuasive function.
Advertising images are the best illustration of the second function. They don't just denote, but they have very much to do with the connotation function. An image showing a mother and a little child sleeping peacefully, and a bottle of milk on the table near the bed, is meant to suggest that the peace of their sleep is a result of their drinking the respective brand of milk that contains everything necessary both to the adult and to the child's health. And it is meant, of course, to persuade us buy the respective brand of milk. ...Show more