Dispositio

Dispositio is the system used for the organization of arguments in Western classical rhetoric. The word is Latin, and can be translated as "organization" or "arrangement".
It is the second of five canons of classical rhetoric (the first being inventio, and the remaining being elocutio, memoria, and pronuntiatio) that concern the crafting and delivery of speeches and writing.
The first part of any rhetorical exercise was to discover the proper arguments to use, which was done under the formalized methods of "inventio". The next problem facing the orator or writer was to select various arguments and organize them into an effective discourse.
Aristotle.
Aristotle defined two essential parts of a discourse: the statement of the case and the proof of the case. For example, in a legal argument, a prosecutor must first declare the charges against the defendant and provide the relevant facts; then he must present the evidence that proves guilt. Aristotle allowed that in practice most discourse also requires an introduction and a conclusion.
Latin rhetoric.
Later writers on rhetoric, such as Cicero and Quintilian refined this organizational scheme even further, so that there were eventually six parts:
While this structure might appear to be highly rigid (and certainly some writers on the subject were overly pedantic), it was in practice a flexible model. Cicero and Quintilian, for example, encouraged writers to rearrange the structure when it strengthened their case: for instance, if the opposing arguments were known to be powerful, it might be better to place the refutation before the proof.
Within each major part, there were additional tactics that might be employed. For instance, a prosecutor might sum up his case with forceful repetition of his main points using a technique known as "accumulatio". The defense attorney in the same case might use a different approach in his summation.
Finally, "dispositio" was also seen as an iterative process, particularly in conjunction with "inventio". The very process of organizing arguments might lead to the need to discover and research new ones. An orator would refine his arguments and their organization until they were properly arranged. He would then proceed to those areas that we generally associate with rhetoric today—the development of the style and delivery of the arguments.
"Exordium".
The "exordium" (; meaning "beginning" in Latin; from "exordiri", meaning "to begin") was the introductory portion of an oration. The term is Latin and the Greek equivalent was called the "proem" or "prooimion". 
In the "exordium", the orator lays out the purpose of the discourse. In doing this, they need to consider several things:
In short, the "exordium" was the portion of the discourse in which the orator would prepare the audience to hear his arguments in a favorable frame of mind. "An exordium can serve different kinds of functions in the differing species of rhetoric, but in all of them some of the major themes of the coming discourse will be announced in advance".
"Peroratio".
The "peroratio" ("peroration"), as the final part of a speech, had two main purposes in classical rhetoric: to remind the audience of the main points of the speech ("recapitulatio") and to influence their emotions ("affectus"). The role of the peroration was defined by Greek writers on rhetoric, who called it "epilogos"; but it is most often associated with Roman orators, who made frequent use of emotional appeals. A famous example was the speech of Marcus Antonius in defence of Aquillius, during which Antonius tore open the tunic of Aquillius to reveal his battle scars.
In the first century B.C. it was common for two or more speakers to appear on each side in major court cases. In such cases it was considered a mark of honour to be asked to deliver the peroration.