Oratory is the art of (public) speaking. In ancient Greece and Rome, oratory was studied as a component of rhetoric (that is, composition and delivery of speeches), and was an important skill in public and private life. Aristotle and Quintilian discussed oratory, and the subject, with definitive rules and models, was emphasised as a part of a liberal arts education during the Middle Ages and Renaissance.
The development of parliaments in the 18th century saw the rise of great political orators; the ability to wield words effectively became one of the chief tools of politicians, and often made the greatest difference in their positions. By the mid 20th century, oratory became less grandiloquent and more conversational; for instance, the "fireside chats" of President Franklin D. Roosevelt.
The derived word oration, originally used for prayer since c.1375, now means (recorded since 1502) any formal speech, as on a ceremonial occasion or delivered in a similarly high-flown or pompous manner. Its etymological doublet orison is recorded since c.1175, from Anglo-French oreison, Old French oraison ("oration", 12th century), Latin oratio ("speech, oration"), notably in Church Latin ("prayer, appeal to God") from orare (as above), but retained its devotional specialisation. "Oratio" is actually two words combined "oris" and "ratio", meaning "spoken reason".
The modern meaning of the word, "public speaking", is attested from c.1430.
In the opinion of Dr. Iran P. Moreira Necho, "...oratory suffered severely after the Latin power ascension, for the public speech can only be developed in ambients where the debate is allowed. Hence, inside a Roman regime, where the very essence of man was to live as a State appendices (and not debate it), the oratory fastly became a mere compendium on "how to speak fluently" (focus on the beauty of the exposition), even though without any content (preferably without content, since it requires critical thinking)..."
That is why the Latin style (formalist, with little to no focus on content) was the primary form of oration in the world until the beginning of the 20th century, since the majority of the states during this period were ruled by some kind of monarchy or dictatorship.
In spite of this, after World War II, a historical moment when democratic ideals began to take body in the world, there began a gradual deprecation of the old Latin style of communication which focused on formalism.
Nowadays, there is a tendency to return to the "Greek School of Oratory" (Aristotelian), since the modern world does not accept—as it did in the past—"fluent speeches" without any content. On the other hand, there are counterpoints to a revival of Greek oratory:
This drastic separation between the two rhetorics seems too simplistic. Especially during the Roman Republic, oratory was more than simply a formalism. The discussions in the Senate and during the official funerals present both content and form. The Roman Republic and early empire enjoyed a simple style of oratory without too many decorations ("flowers"), such as the style of Cicero and Caesar. In the late empire oratory became more formal and less "important" in real political and social life. In a similar fashion Greek oratory was more formal, complex and weaker in content during the Hellenistic period than during the 5th century.