I'm not keen on the idea of the Mageborn. Maybe it's my semi-socialist upbringing: What abaht the workers? Or my Canadian background: Who do you think you are?
Whatever the origin, the dubiety is similar to my feelings about genius in art. Nice if you've got it, but irrelevant to the learning of the craft. I rather mistrust the assumption of genius, because it seems to be taken as an easy out--you can't teach someone to be a genius, therefore genius can't be taught. At worst, anyone who isn't a genius isn't worth teaching, the genius doesn't need teaching, and the teaching of the craft is lost.
If that sounds far-fetched, read Jonathan Stephenson's opening essay to Materials and Techniques of Painting, describing how painters lost the knowledge of grinding and mixing pigments, making brushes, and preparing canvas and panel, and how an artisan's craft became a gentleman's hobby. And how that knowledge was painfully regained from the study of a few surviving artists' handbooks and analysis of paint on manuscripts, panels and canvas.
What attracts me to the guild system, and to the idea of apprenticeship, is that it assumes that all crafts are equally accessible. Some apprenticeships are longer than others (a tiler is only a few months, others may be 5 or 7 years) but provided the apprentice is sound of wind and limb, and willing to work, at the end of it he's turned out as master (later as journeyman) capable of earning his living, whether by making shoes, casting pewter, tanning leather or painting altarpieces.
Masterpiece once meant a competent work showing mastery of the materials and techniques proving one's readiness to set up shop. Nowadays it means something brilliant and outstanding, original and elite.
But that is a many-layered rant, and I digress.
The idea that only the mageborn can do magic is, to me, like the idea that only a genius can paint or play an instrument. If you have perfect pitch, you'll learn to sing faster than someone who has to begin with scales, sure. Genius exists, and talent exists, but while that gives you a leg up, it doesn't take you to mastery without study and practice. If you don't master your materials and study your techniques, you'll fall behind the 'untalented' student who is willing to do the work. (There's a quote from Wee Free Men applicable here, but I leave it as an exercise to the reader.)
The idea that two people can recite the same words, or make the same gestures, or draw the same circle on the ground, and that one of them is successful and the other isn't, because of some inborn quality in one of them, is not an idea that works for me. It's like saying that you and I can pick up a paintbrush, dip it in the paint, and my brush will make a mark on the canvas and yours won't. Or you and I can sit down at the piano, and your keys will make lovely chiming noises and mine will make a dull thud. Assuming here that both of us have rudimentary training and recognise the different keys, that isn't a plausible result. Come to that, if two untrained people pick up violins, I'd bet that even the musical genius of the pair will not, first try, sound lovely.
You'll note that I'm not using, here, the definition of genius as 'an infinite capacity for taking pains'. I'm using genius in the Romantic sense. I'm all fine with the idea of genius as an infinite capacity for taking pains--and I'm not a genius in that sense either, because I'm lazy and easily discouraged.
Some writers make the Mageborn concept work. I don't mind it in Barbara Hambly's books, in part because she doesn't make it easy--there's years of study and in the Unschooled Wizard series, there's a brutal ordeal followed by years of study. Hambly also plays with a persecuted minority subtext, which you could read as Jews or as gays without much difficulty. That gets risky in lesser (naming no names) hands, because it can too easily turn into 'oh woe, I am enormously powerful and must now angst about the responsibility and how everyone hates me' which is boring and makes me want to smack said characters (a poor plan, because they're both enormously powerful and immature). On the whole, I think Hambly does it well and avoids the traps. It doesn't hurt that she's a damn good writer.
I don't think I could make it work, because I can't follow through with the system. I'd keep fussing about details and genetics and logic. I like the concept of magic as learned craft, and I like folkloric magic, though I can't claim to be any sort of authority on it. Only that when I read about it, it seems to fit together, to make sense to a non-rational part of my brain.
An interesting thing about what I might call documentable magic (surviving grimoires and folk practices) is that it doesn't seem to concern itself particularly with the sort of things that fictional magic-users do. (Admission of bias: when I read the word 'magic-user' in fiction I twitch, because to the best of my knowledge, the phrase was created by the authors of gaming manuals. It's not in the OED, which does list the more evocative 'magic-monger', and also gives 'magic' as an adjective meaning 'addicted to magic', which provides an interesting slant on 'magic-user'.)
Folk magic divination is used to discover how long one may live and who one will marry, and what the weather will be. Charms are used against illness or injury, against theft or to recover lost or stolen items, to make crops grow and to keep animals healthy, to gain someone's affection (or lust), to bring on or avoid pregnancy. This is all rather petty and commonplace compared to what magicians in fantasy novels or FRP games do. No casting of fireballs, no petrification, no raising armies of the dead.... No tech-substitutes like wards that act like tripwires, or communication via crystals.
To generalise horribly, folk magic concerns itself with basic survival, food and shelter. Grimoire magic concerns itself with gaining influence and power over others. FRP magic seems to be most concerned with winning battles--naturally, since FRPs are largely combat and quest-based. FRP games do view magic-user as a craft, something learnt rather than inborn, due to the mechanics of the game. And due to the mechanics of the game, the learning part tends to be backstory.
To generalise even more horribly, some sizeable percentage of modern epic fantasy seems to have the same structure and needs as an FRP campaign, with the addition of magic being an inborn gift, rather like being the True King but without a validating prophecy. But I don't read that much epic/high fantasy, so I'm probably biased, misled by the back-cover blurbs and a quick thumb-through.
I'm drawn to humble magic, useful everyday magic. That's what makes sense to me, but I can see that it isn't as exciting as fireballs and darkness-by-day and other cool CGI effects.
You do find some fairly high-end magic in folktales. Petrification, yep, transformation, yep, sleeping for a hundred years, yep, bringing the dead to life, yep. The mechanics are not explained, and sometimes the internal logic of the story is a little shaky. Magicians are rare in folktales; witches are common indeed. There are also random characters not identified as magicians or wizards, who still employ magic. Cooks, princes, daughters of ogres, peasant girls and enchanted animals, any of them may have a handy spell for good or ill. While there aren't many designated magicians, the contest of magic shows up fairly frequently--at least, that's how I interpret the chase and disguise sequences where one character throws down a magic item to delay pursuit, or transforms herself to mislead pursuers (Fundevogel). I don't know whether Stith Thompson would agree.
Medieval romances (of which I have read maybe half-a-dozen) have magic elements. Some flashy, like transformation, and some lower-level practical jokes, like gowns or goblets that reveal infidelity (always good for a laugh). Some useful, like shields that can't be broken, or belts that prevent injury. Magicians seem to be rather more common, witches rare. I have the impression that magic is more often the plot device that starts the trouble and the plot, rather than resolves it, but I haven't read enough to validate or disprove the impression.
The courtly fairytales (Perrault, Madame d'Aulnoy) (really good Terri Windling essay here) were fond of stage dressing and gadgets, seven-league boots and caps of invisibility--swiped from Greek hero-tales, perhaps?--and those were adopted by the literary fairytale writers like Andrew Lang and Dinah Mulock Craik.
Gadgets seem to have been dropped in modern fantasy in favour of what the Tough Guide calls Quest Objects. I'm not sure why, perhaps because of a lack of acquaintance with the classics, perhaps because they might have made things too easy, too apt to be solved within a single volume. The written fairytales used more magicians and wizards than they do witches, and magic starts the trouble often enough, as do magic beasts like dragons. Force of arms and virtue, sometimes aided by gadgets, sort things out. The clever peasant girl and the lucky simpleton don't get so much love here--back to the folktales for them.
Which brings me back, I guess. Folktales are often about the triumph of the humble, the simpleton winning the clever princess, the old soldier beating out the Devil, the clever peasant girl winning the king, the unfavoured child rewarded for a kind act.
Anglo-Saxon Magic, by Dr. G. Storms, published Martinus Nijhoff, 1948 - The first chapter is a concise introduction to common concepts of magic, the uses of spittle, blood, dirt, water and silence. Almost all the charms are concerned with protection against illness, theft, and general harm. Life is precarious.
The Galdrabok: an Icelandic Grimoire, by Stephen Flowers, published Samuel Weiser, 1989 - This is 'book magic', relying almost entirely on runes and signs. It doesn't portray the magicians as particularly benevolent or enlightened, since the majority of spells are intended to gain the favour of the powerful, find out thieves, and play unpleasant practical jokes (oh, and force women to sleep with you.)
English Folk-Rhymes, by G. F. Northall, published Kegan Paul 1892 (reprinted) "A collection of traditional verses relating to places and persons, customs, superstitions, etc." Ch.4 on superstitions includes charms and spells, and, slightly cloaked in Latin, a very down-to-earth spell for gaining the affection of a young man. Some of the other sections include rhymes that look very like spells, and could be easily adapted.
The Secret Common-Wealth & A Short Treatise of Charms and Spels, by Robert Kirk, published D.S. Brewer for the Folklore Society, 1976 - Short, as it says, but ties in nicely with the other sources. Mostly of interest for the first section, his account of Fairies and Elves.
The Fate of the Dead, by Theo Brown, published Brewer for the Folklore Society, 1979 - "A study in folk-eschatology in the West Country after the Reformation" and utterly fascinating (I'll probably blog just about this book at some point) in its examination of the folk beliefs about book-learning and the power of the printed word. An unmarried Oxford graduate is the best man to banish a ghost, in case you were wondering.
The Pattern Under the Plough, by George Ewart Evans, published Faber, 1966 - a small but dense book showing how belief in magical protections and encouragements is woven into rural life in East Anglia. Hagstones, witch-bottles, threshold burials, and how to jade a horse.