It is interesting to note, however, that in every recorded instance, a sorcerer only derives power from one type of extrinsic source. For instance, a sorcerer who draws his strength from growing things will find himself considerably weakened when placed within a desert environment. Theoretically, this is an example of the law of conservation of powers, which predicts that absolute power will always be prohibited within a balanced natural world.
Origins and Explanations:
While there are many theories regarding the origins of sorcerers, none have been conclusively proven. All such theories, however, can be broken up into two predominant categories: the Serendipitous and the Causational.
The Serendipitous theory states that a sorcerer is always created when a certain series of variable requirements are met. The most well-known Serendipitous theory is the "seventh son of a seventh son" premise, which merely states that any seventh male offspring of a wizard who is, himself, a seventh male offspring will, without exception, be a sorcerer. Other theories are far more complicated, suggesting deviations in times of the year, phases of the moon, ages and lineage of the parents, and even the number of windows in the room of the child's birth.
Adherents to the Causational theory, however, postulate a much different origin, owing itself not at all to randomly determined variables but to the balance of the magical world in general. In short, the Causational theory states that when the scales of the cosmos require a sorcerer (either to maintain balance or to destroy it), then a sorcerer will, out of sheer necessity, appear.
Notably, one variation of the Causational theory adds that there can never be only one sorcerer. In order for the polarities of destiny to remain in check (the theory claims) there must always be a duality: either no sorcerers whatsoever or two. This theory, however, like all the rest, has never been proven or disproven.
Historical Examples:
While any number of legendary sorcerers have appeared in the annals of history, there are very few documented cases of the existence of such individuals. The most well-known and verified instance is Merlinus Ambrosius, whose powers, mysterious origins, and legendary disappearance describe the very archetype of the classical sorcerer.
During his lifetime, he was known to conjure feats of such devastating natural ferocity, including (but not limited to) earthquakes, floods, typhoons, walking forests, and tidal waves, that he was by turns revered and/or vilified by all who knew of him. Since his time (approximately 935-980 AD) there has been no uncontested evidence of another living sorcerer.
Variations—Elves, Goblins, Sorceresses
While both elvenkind and goblinkind also derive their powers from extrinsic magical sources, they are not technically considered sorcerers (despite long-standing arguments by goblin leaders and species rights advocates). Since both goblins and elves can only contain the equivalent of any average magical person's power, they do not meet the 'Limitless Magical Expression requirement' (set forth by the Magical Defining Characteristics Census of 1177) for sorcerer status.
Contrariwise, there has existed a long-standing theory that claims that the existence of sorcerers implies, by logical necessity, the possibility of sorceresses—that is, a female whose source of power is extrinsic and who is capable of summoning limitless expressions of that extrinsic resource based upon its availability. Despite this, no irrefutable example of such a person has ever been verified.
James lowered the book and leaned slowly back, letting his head bump the bookshelf behind him. For several seconds, he merely stared up past the canyon of the leaning bookcases toward the books which flapped silently through the library's upper levels, winging toward their shelves.
It made perfect sense. That was the most dreadful part. The passage in the encyclopedia was like the center piece of a puzzle, the one that brought all the separate bits together and formed the full picture. As incredible as it seemed—as completely gut-wrenchingly unbelievable as it would appear to any sane observer—Petra Morganstern… was a sorceress.
James shook his head slowly, barely able to grasp the concept.
He remembered the first time he had met Petra, back on his first night at Hogwarts. Ted had introduced her to him along with the rest of the Gremlins. She had seemed merely pretty and smart then, the perfect foil for the brash insolence of the rest of the Gremlins. James had had classes with her throughout that year. In all honesty, he had begun, even then, to feel the faintest stirrings of romantic magnetism toward her. Most assuredly, there was something unique about her— something rare and slightly dark, both inspiring and solemn. Even so, how could this slight, smart girl—the one with the tendency to suck thoughtfully on the ends of her raven-dark hair and doodle dancing elves in the margins of her textbooks—how could that girl possibly be something so powerful, so rare, and so potentially frightening as a sorceress?
And yet, of course, James knew it was true. It had to be true. Everything pointed to it, from the mysteries surrounding her last day at Morganstern Farm to the amazing magic she seemed to perform without any wand to the strange silver thread that had appeared when she'd fallen from the back of the Gwyndemere—conjured by James, but drawn, apparently, from her own power.
Merlin, of course, was a sorcerer. Was that why he was so interested in Petra? Was that why he was worried about what she might do? Was she his equal? His opposite?
James shuddered, violently, and the encyclopedia nearly fell off his lap. Instinctively, he grabbed at it and then closed it with a soft thump.
For the first time, seriously, he wondered if Petra really had been involved in the attack on the Vault of Destinies. Thus far, James had been able to convince himself that it couldn't really have been her that he'd seen on that night coming out of the Archive alongside the creepy woman in the black robes. He'd convinced himself that it had to have been a trick—someone using Polyjuice Potion, for instance, or perhaps even a Visum-ineptio charm. But what if none of that was true? What if Petra really was in league with the mysterious dark woman, and had been lying all along about her innocence? Worse, what if the Morgan part of Petra's mind, the part influenced by the final shred of Lord Voldemort's soul, had broken free of the mental prison that Petra had erected for it—the black castle in her dreams—and had taken over somehow?
What if James, Ralph, and Zane succeeded in breaking through to the World Between the Worlds only to find irrefutable proof that it had been Petra (Morgan) who had broken into the Hall of Archives, cursed Mr. Henredon, and then stolen the crimson thread from the foreign dimension's Vault of Destinies? What then? Would the courts send Petra to wizarding prison?