To the extent that there is a substance to declamation, it is in the rehearsal of commonplaces, in the performance before peers, in the reproduction of the spirit of the declamatory venue itself.
Declamation, Paternity, and Roman Identity: Authority and the Rhetorical Self, Erik Gunderson.

Declamation

A declamation is a speech given before admirers, rivals, friends, in private or before a more general audience in public. The subject matter is fictional and the goal is applause. It descends from epideictic, but whereas epideictic speeches are meant to serve the community, declamations are composed to bring admiration to the speaker, although in some cases, if the performance was particularly good and there was an important person or delegation in the audience, the community might bask in reflected glory. A sophist of renown was a great draw for any city. Declamation is also a genre of rhetorical instruction, the culminating exercise, the capstone. Thus the history of declamation offers insight into the history of rhetoric in general.

In the early days of rhetorical instruction, one learned by watching and listening to one's elders. By Socrates' time eloquent individuals (sophists) were starting to draw crowds and to profit from those crowds. The famous man would give a speech and the audience would make notes, perhaps memorize it verbatim or even write as much down as they could. The opening section of Plato's Phaedrus is the source of this assertion. In Gorgias, Plato has the eponymous character say, give me a subject, any subject, and I will make up a speech on the spot. Giving and receiving speeches as a from of entertainment and instruction became popular all over the Mediterranean, wherever Greek instruction was available.

By the late Hellenistic period (Death of Alexander 323 BCE to Death of Cleopatra 30 BCE), many of the major cities were providing some kind of organized rhetorical instruction, often overseen by a head rhetorician who employed teaching assistants, paying for them with part of his civic stipend. By the time of the second sophistic (late 300s early 400s AD), schools were common in the larger cities. Greek was the language of instruction (hence "Hellenism") and knowing how to demonstrate your learning was an important social marker, a bit like being able to talk sports today or being able to play a decent riff on a guitar or how to make a tiktok video.

The standard curriculum in these schools, known as the progymnasmata, consisted of 14 exercises, starting with reading and reciting and eventually writing fables, then anecdotes (chriea), and so on up levels of complexity. Schools were typically one room-school-house like settings, where the younger students worked on the preliminary exercises and the older ones helped them and worked on their own, more advanced, exercises. When a student was sufficiently advanced, he would start writing and giving declamations. We know that Libanius of Antioch was sent to Athens to learn rhetoric and when he eventually returned he was asked to give a public declamation (a dokimasia) as evidence of his accomplishments and as a sign that the city had made a good investment in him. We have, however, only a handful of extant declamations.

We have three sources of examples of Roman declamation: Seneca the Elder, Pseudo Quintilian, and Culpurnius Flaccus. We also have many references to the practice. We know that successful, educated people practiced declaiming long after graduating, as an after-dinner entertainment, as a competitive game, Not unlike poetry slams, or roasting, or Drop the Mic ala James Cordan (You tube it if you can't conjure it from memory.) and as a way of showing off one's learning and experience and therefore affirming one's identity as a member of the class of educated people (an aristocrat, in Greek), as well as a form of intellectual exercise to keep one's wits and tongue at the ready in case some enterprise required them.

Here's an example of a declamation assignment from Culpurnius Flaccus (lived during Hadrian's reign, 76 - 138 CE) See the Wiki Article. Btw, Flaccus translates to "limp," as in flaccid. The Romans were fond of pointed nicknames. Biblius, drunkard, was not uncommon. The name Crassus, which was hung on the Jeff Bezos of Cicero's time, meant fatty. While Marcus Tullius himself is still known to the world as cici or chickpea (Cicer arietinum, hence Cicero) because of a mole on his face.)

46 THE RAPIST’S SON, CONDEMNED WITHOUT A TRIAL

The Laws:
1. The law concerning raped women.
2. One may execute one's’s children without a trial.

The Situation:
A certain man committed rape and then ran away. From the rape the girl conceived a child and gave birth. Then the rapist returned, the girl demanded his death. The man wants to execute his son without a trial. The rape victim opposes this. (trl. adapted from Sussman).link

A student would be given something like this, perhaps in the morning, told to prepare both the accusation and the defense, and then, perhaps, required to perform both in the late afternoon.

The editor and translator explains:

Roman declamation can rely on its audience's awareness of its generic conventions: pirates, ghosts, evil stepmothers, blind sons and violent tyrants people a world as weird as it is wonderful and provide ample fodder for teachers of rhetoric and their students. They discuss (in all seriousness) fictional court cases so as to provide training to future lawyers and display a firework of rhetorical skill. When read sociologically, rhetorical education fosters social reproduction and helps to shape a young man's attitudes and behavior; it teaches him how to be a Roman citizen.

Consisting of just fifty-three short excerpts of declamations, Calpurnius' oeuvre in many respects epitomizes Roman Declamation: it exemplifies all its traits and due to its relative brevity also provides a potted version of the genre. Therefore we hope that readers will accept our invitation to read Roman declamation as literature and not just as offering a convenient footnote when on the hunt for a reference on racial prejudice in antiquity (cf. Calp. 2).

This last point seems oddly specific, as though Dinter had some particular article in mind. It's quite possible, though I don't know because I don't read much in this area, that many classics scholars have of late been decrying the world seemingly reflected in these outlandish and lurid speeches. Indeed, arguing about how to interpret the remaining declamations has become a cottage industry.

As a genre situated at the crossroad of rhetoric and fiction, declamation offers the freedom and ability to experiment new forms of discourse, and calls for both a technical and literary analysis. If one places the literariness of declamation to the spotlight (van Mal-Maeder 2007) -- declamatio has been hailed by Bloomer as ‘the first literary movement of the Roman empire’(2007: 297) -- it becomes possible to study it as a realm of genuine literary creation with its own theoretical underpinning, rather than simply reading it as a gratuitous exercise mimicking the practice of real orators.

Dinter, Martin T., et al. Reading Roman Declamation - Calpurnius Flaccus. De Gruyter, 2017.

Declamation, as a practice and as a goal of education, seems to contrast vividly with Athenian rhetorical instruction, Donald Russell, who wrote one of the most important relatively recent books on declamation blames Seneca the Elder for reducing declamatio to 'a toy model of oratory.' Someone else, Seneca himself (or was it Quintilian?) says declamation no better prepares one for oratory than fighting with wooden swords prepares one for battle. "How you 'spect to run with the wolves come night when you spend all day sporting with the puppies?" Omar Little, The Wire in the Isocratian form at least, the goal of which was civic engagement, direct participation in collective decision making learned by writing and presenting speeches on current affairs, political alliances, financial concerns, warfare, and so on. Educated Romans did participate in collective decision making and it would be incorrect or at least hasty to assume that those trained in declamation were merely practicing a florid predecessor to the novel. The sophists of the second sophistic were important members of the city that employed them (Libanius and Aristides, for example), frequently using their oratorical skills to garner Imperial favors for their city. Several sophists had statues erected in their honor. And yet, many of the declamations left to us suggest that over time declamation became untethered from reality or perhaps it entered it's own virtual reality.

D. A. Russell argues in Greek Declamation that part of the learning experience of declamation was speaking and writing in different voices, perhaps of trying to understand the world from different perspectives:

Pretending to be someone else, and composing imaginary speeches in character, is an essential part of most literary activity. It is important not only in drama, epic and fiction, but also, at least in ancient times, in lyric poetry, history and philosophy. But it also has an educational function. Where public speech is important (as in the Greco-Roman world), it is important to train people in its skills. What better way than by inventing situations and giving one's pupils parts to play? And, since what is taught in school has at least some impact on what people do elsewhere, the practice, like other rhetorical practices, may be expected to have an influence on literature, and it is for this reason that scholars other than specialist students of rhetoric have found it of interest.

. . .

But there was a feature of [declamation] present in school practice but even more important in the literary development of the form, which ran counter to this concern with argumentation: these speeches were always impersonations. The declaimer never appears in his own person, but always as some historical character or stock type. He becomes Themistocles or Alcibiades, Honest Poor Man or Old Miser. Less often, he becomes an advocate (synögoros), a comparatively colourless rôle, only adopted when the circumstances demand it. Women usually need advocates, as they could not appear in court; but this rule is sometimes broken, as in the case of the mother who has killed her prostitute son in the gymnasium, whither he had fled for sanctuary because women were not allowed in. Another special case is the rhetor who has had his tongue cut out; the convicted offender whose sentence is still at issue needs an advocate is debated at some length by a teacher who adduces Demosthenic parallels and finally decides to let the poor man speak for himself [huh?]. Advocates are thus exceptional; as a rule the declaimer plays a part and displays a strong and distinctive ēthos. Now this might be not bad practice for an Attic speech-writer of the classical period, who needed to give his client words and thoughts not too inappropriate to his age and status; but for most of the pupils who practiced declamation through the Hellenistic and Roman period, it had no practical relevance at all. What it did do was to strengthen the tendency of the exercise to become literature, to turn it into a dramatic monologue with a plot. This development reaches its peak in Libanius, in whom ēthos predominates over everything else, and we get a corpus of speeches intended not only to amuse but to endure as literature.

At any rate, I find declamations hard to read because they are so over-written, so histrionic (a word used by scholars for centuries), so melodramatic and so gratuitously violent that I really don't know what I'm reading. Are they literature? Are they rhetoric? Are they expressions of identity, displays of cultural capital, techniques of social construction? For years scholars have argued they are evidence of the decline of Roman culture, from the golden to the silver era or Roman literature. Declamation might be all of these things or something else entirely. But they are weird.

Consider Pseudo Quintilian's "Declamation 10." The setup for this controversia is strange for us but might have been merely an interesting puzzle to its intended audience.

A child has died and been cremated by the mother and father. Then the mother sees their child's ghost at night, several nights in a row. She asks the father if he has seen it too. The father hasn't and thinks his wife is grief-stricken. He hires a magician to keep the apparition away. The wife sues the husband for, well, for what exactly isn't quite clear to me and I can't imagine what law has been broken or if the intended audience cared that such a law must exist for such a court case to be declaimed. The declamation reads to me like an elaborate excuse to speak in several different voices, to practice ekphrasis, and explore psychology and a bit of metaphysics. It isn't really trying to resemble an actual court drama, but rather be a drama set in a court. No judgement of the case is rendered in the end. The mother gets the last word. And that's that.

Here is a snippet:

Think with what distracted, what admirable fondness, the woman would at one time be hanging over his death-pale features and tearing her woe-begone eyes, at another complaining that it was all in vain that her breast had been drained to suckle him, then again would aim blows at the womb which could survive the death of its offspring. (Pseudo Quintilian, Declamation 10, C.3.)

If you have the time and inclination, here is a link to Pseudo Quintilian, Declamation X, in its entirety. Browse it at least.

As I see it, as a pedagogy, declamation is a kind of rhetorical problem set. You give the student a complex, contradictory situation and she or he has to compose a speech or a pair of contrasting speeches more or less on the spot, like a five paragraph essay on steroids. The setup for modern students, needn't be lurid, and certainly the rapists and pirates of old have no place in our world. Still, the exercise -- given this scenario and this context and this audience, compose contrasting speeches -- continues to have considerable merit. The contrasting speeches (or essays) part is critical because today people tend to rant, to amplify their own position and vilify or pathologize the opposing positions if they think of them at all rather than asking careful questions of all points of view in order to elevate their understanding before formulating an opinion.

Declamation's best source is Seneca The Elder's Controversae and Suasoria. Seneca lived on the hinge between the Hellenistic period and the Second Sophistic (54 BC – c. 39 AD). You should read the material linked below to get a clearer impression of declamation.

Seneca the Elder, Controversae and Suasoria. That link includes a section of the editor and translator's introduction to the test, which is an excellent overview of declamation. It also includes Seneca's introduction. The full text is under copyright.

Declamation

Further Reading