Although pleading a case before the assembly was originally the main function of Greek Rhetoric, the idea of an "assembly" is for us merely a metaphor. The truth is that, unless we are lawyers, we do not, normally, literally appear before such an assembly; but we do figuratively. In fact, giving a speech or even just trying to persuade your friends is like pleading a case, and hence requires the use of rhetoric. As an analogy, consider the idea of creating a garden, which will be our primary metaphor here. In designing a garden and building it in such a way that when it is in full bloom it captivates its visitors, our task, though obviously not a linguistic one, is not unlike using rhetoric to argue a case convincingly. The garden represents the main idea in our argument; and the different features of the garden—plants and trees and ponds—are analogous to the reasons and evidence we use to support our claim. And just as in pleading a case we use words and exhibits to assist us in making our points, so in our garden we would have some highly colorful features—the flowers—that stand out visually, as well as less visual features that make subtler statements, like stands of trees or outcrops of rocks.

This garden metaphor is quite useful, but it will work best as a model of "invoking" if our intention is to model our garden after a real location. This is a necessary requirement, for in pleading a case we use our words and exhibits to invoke a mental model, as it were, of a real situation. And building a garden, in this sense, would mean making a model of a real location so that any visitors to the garden would think they were really at that actual site. Thus, the technique of modeling plays, along with words and exhibits, a key role in Rhetoric; and models will be among the basic tools of the trade the rhetor uses to build his or her arguments. In more precise words, in order to persuade an audience to accept his or her position on a particular case, the rhetor will employ words and exhibits, verbal and visual images, to create and convey a model of the situation which he or she holds to be the case.