"Transfiguration is the art of bending the fabric of the universe to your will."
I say this to every class I teach, and every guest lecture I find myself speaking. Transfiguration is the most powerful of the arts, it changes reality with every motion, rupturing what has existed for untold centuries with magic. The Greeks feared the subject, banning the practice from all but the most credible of practitioners. Those few were revered as gods amongst mortals, chief of whom is known today as Hephaestus.
The dark secret no Greek wanted an outsider to know, was that every blacksmith mage held at least a minor talent in Transfiguration. Making bronze was a muggle secret, but every wizard smith could manufacture such a thing. The best could hold a Transfiguration for years, but the inevitable degradation necessitated experimentation. Among the Greeks, this was a thing of beauty despite their reticence. Creating a new substance is exponentially easier when the base elements can be created from base materials – experimenting with Transfiguration however frequently wound up with broken bones and hideous creatures.
When Rome took on the onus of responsibility for the Greeks, they also acquired the research material. Many secrets are gone; the battles between Olympus and the Temple of Mars rendered entire cities into rubble. Several members of Olympus survived the battles and became part of the Temple of Mars. While the Roman faction proved superior in combat, the Greek thought-mode gained the advantage, from which we arrive to so many similarities between pantheons.
As an aside, any further inquiries in the change of power from Olympus to the Temple of Mars-orders would do well to read Infernum, magister Magics. Not all the change in opinion came from pure culture, after all.
The history of Transfiguration continued in a similar fashion, practiced solely by Masters and their Apprentices until the Fall of the Muggle Roman Empire. Wizards survived the Fall with ease, forming conclaves outside of Latin infrastructures and creating competitive strongholds. Many of these ran afoul of Germanic tribes, persistently misunderstanding the primal origins of their magic. Organized Roman protocols held back the barbarian hordes for millennia, but when a full regiment of Acie divinos lacked a shield-wall to stand behind, the erratic chaos inherent within a single Nordic mage could alter the flow of battle in a single spell. But many powerful members of the former Roman Temple of Rome treated with the barbarians and gained aid.
To date, those families have descendants to this day and age, if changed in name. The Potters (Paters), Malfoys (formerly Drako; see Name Changes and Origins for more details) and Jullan (Julian) lines all trace origins to the Roman antecedents. Powerful Germanic families like the Blacks (Blæc) and Dumbledore (Dumbelandor) may claim some lineage to the Latins, but stretch much further back in their Germanic ancestry, in cases as far as what was considered more civilized regions.
Note: the Germanic tribes considered the Latins soft and unfit for trust as a rule. See Customs of the Germans by Tacitus Altos.
The strong Transfiguration abilities of certain Latin families astounded their new neighbors. Changing a battlefield from a field of grass into an army of rampaging golems tends to do that – and secured alliances. Of course, once established, these alliances demanded to share in the knowledge of Transfiguration, which was equated to a strength of equal value as Divination in that day and age. Granting those skillsets took mages of prodigious power, allowing only the strongest to survive yet treasuring every mage born.
The greatest of these was Merlin, also known as Emrys or Ambrosius, a genius in many areas. But his talent in Transfiguration made him a legend in his own time; a single wizard that could change not only the battlefield but warded and charmed holdings proved a Power in his own right. No king or mage could overpower him, and wherever he turned his attention quaked at his passing. The three greatest benefits to the field of Transfiguration since their development in Grecian times came from this one wizard.
First, Merlin established the boundary of living and non-living materials. Through his studies the thaum became a standard of measurement, capable of precisely describing limits to Transfiguration durations and how great a change could be inflicted by a particular wizard or witch.
Second, Merlin described a concept that took three centuries to rediscover: the relationship between the stars and Transfiguration. Evidence from observations show that Merlin well understood the reflective nature between constellations and creations imbued via Transfiguration. The now commonly known 'As Above' principle (attributed to Magess Aich'n Delacour) intensifies the amount of magic buried within a Transfiguration, extending a shift by a factor of three. Special occasions may extend the effect by a factor of seven, and in rare situations, can be compounded again into variables of thirteen. The end result of the last factor is invariably destructive upon the caster, which is how Merlin defeated the Warlock of Kent without casting a single spell (see: Famous Battles in the Post-Roman Era, by Phoenix Darkling).
Third, the initial limitations of creation were made firm under Merlin's supervision. Gold cannot be Transfigured from plant material in the initial casting, and the reverse is equally true. His lecture to the Third Court of Londinium established the now well-known Rule of Increasing Power. The more Noble an element, the more magic is required. The greatest example he provided lay in the conversion of simple copper to gold; fifty thaum were required for such a thing. Yet the conversion of gold to copper took a mere ten thaum, and the further conversion of copper to iron took less than a single thaum.
This established properties of Transfiguration, but did not elucidate the general principles. At that time a full dozen wizards could be considered Masters of Transfiguration, and each trained their own apprentices in their own way.
Further expansions on the pool of Transfiguration knowledge remained stagnant until the 20th century. Chaos from the re-organization of Muggle culture and the disappearance of Merlin from the world-stage forced the wizarding attention to matters of survival and cooperation. The disruption initiated by the Statue of Secrecy in the 17th century came on the heels of over two centuries of increasing conflict, developments in wards, charms, potions and all manner of marvelous innovations in Arithmancy. Masters in Transfiguration grew confident in their craft, but such individuals remained at the edge of society. Transfiguration's use was of limited value as alternative methods for procuring materials grew prevalent.
At the cusp of the change between the 17th and 18th centuries, the Gamp family came upon the scene. A new line from the distaff Meddorin family and a muggleborn wizard, the firstborn developed an intense interest in Transfiguration. Despite discouragement by multiple parties, the son became enamored of the subject, experimenting with the sort of energy rarely seen. Young Aristotle continued training in the art, growing in its subtleties until he finally made a discovery, one that shook the very foundations of Transfiguration. By reducing the known principles of Transfiguration into a simplified form, he discovered an arithmantic correlation between elements, their absorbance of power, and the stellar bodies that made up the strengthening components of exponential value.
The rediscovery of the 'Lost Secret of Merlin' catapulted the Gamp family into prosperity. Transfiguration became a subject of high interest once more, and a cornerstone of education centers on an international scale. This one discovery caused entire business empires to rise and fall, for with it temporary modifications became known in their full nature.
Unreliable Transfigurations became a thing of the past. With that change came a new burst of prosperity, stretching the already lengthy distance between muggle and wizard. Homes became palaces overnight, owners altering their dwellings merely because they could, not needing to pay exorbitant fees to craftsmen or for ownership of a house elf.
The Masters did not falter under this sudden revelation. Instead, they incorporated this new knowledge and raised their own levels of expertise to unheard of levels. Previous magics believed to have belonged solely to Merlin became entertainments at gatherings, spreading the new popularity even faster. Educational standards increased, turning the subject of Transfiguration into a regular course at the greatest education centers. Hogwarts was the first in 1803, then Beauxbaton in 1805 – although to be fair, the French school had already ensured a private tutoring program for those interested in the subject. Other schools followed suit.
Today Transfiguration is a cornerstone of a well-rounded education. No wizard or witch will be viewed with respect if they cannot accomplish the most basic of changes, and in order to obtain employment, most need to have obtained a minimum of Excellent in their NEWT's. The subject has come into its own after a long, and lonely history.