One of the towering figures of both 20th century jazz and guitar playing is Django Reinhardt. His spectacular playing, even by today's standards, is technically breathtaking. But when the truth is revealed, that he did most of his soloing using only the first two fingers of his fingerboard hand, his dexterity seems impossible. His ring and little finger were damaged in a fire when he was young, and thus, other than a little use during chording, those fingers were useless. His facile playing is thus even more amazing.
From the unlikely source Boing-Boing, we find this link to a clip of Django and his Hot Club de France Quintet ca. 1938 (his fingering style is very clear):
Other info about Reinhardt can be found at wikipedia, as well as many other sites.
To modern guitarists his playing seems prescient. Almost all of the tricks or ornamentations used today, bent notes, trills, hammer on-and-offs, and arpeggiated chords, were used by Reinhardt extensively.
But there is one thing he had that is missing from the repertoire of many of today's otherwise fine players: line. Melody line.
Since the development of blues playing and all its descendents, there has been a tendency to play "positions" or "forms." Blues, based on simplistic Pentatonic scales, provided plenty of variation for most guitarists, while allowing the use of standard fingerings and positions, and "licks" or "riffs.". Upon learning some basic vocabulary of licks and riffs, guitarists could solo in any key merely by moving the riffs up or down the fretboard. Play at the 3rd fret, it's in the key of G. Move to the 8th fret, you're playing in C.
Nothing wrong with this. Listen to Stevie Ray, Jeff, Eric, Jimi, Jimmy, and even today's Pentatonic devotees like Slash, Jack White, or even Prince, and there are plenty of spine tingling riffs to absorb. But listening to Reinhard, who played with a freedom dictated by complete grasp of melody and chords, one is struck by his very inability to play from within positions because of only being able to only use two fingers. He had to move to where the notes were that he was hearing inside his head, rather than play the notes that fell under his position-based fingers.
When I used to teach guitar, starting in my senior year of High School and going on through the first 3 years of college, I used to have students ask: "Why do I need to learn to read music? Eric/Jeff/Jimi et. al. can't read, and they claim that reading music will stifle their creativity."
The answer of course is bullshit. The more tools one has, the more one can create. Eddie/Eric/Edge would be even better players than they already are if they knew the fundamentals of music. Imagine how richer would Clapton's playing have been if he had learned the notes in a V7flat9 chord with explanation by a teacher, instead of accidently stumbling on it one day. Sure, I love self discovery, but it's pretty inefficient. Picasso, as an example, was a superbly skilled classical artist, which later gave him the skills he used to help his talent develop cubism, a new and radical expression of art.
Having said that, a complete understanding of music theory won't make you a great player unless you are already a great player somewhere deep inside, any more than all the hitting instruction on the planet won't make you into Sammy Sosa. Technique, tools, and theory can be taught. Talent can't.
When one really has knowledge of where all the notes are, along with scales, modes, chord substitution theory, then one can play as well as one's talent has to offer. When all you know is basic blues pentatonic positions, that's all you'll play. But if you know blues, and have a great education to back it up, you can play anything.
Any musicians who read this, go back and listen to Django. Don't get sucked in to the whole "Gypsy Style" homage of many of his followers today, because that's not where his greatness lies. Instead, listen to the melody, the soul in the fingers. This guy played rock'n'roll, he got it. He could play that way because to him, the fretboard wasn't positions to riff over, but simply all the available notes. And he clearly knew where all the notes were.
And please, don't think that I don't appreciate the primitive. The Ramones, Link Wray, Dick Dale, Robert Johnson, their talent was transcendent. What I'm talking about is virtuosity, the ability to wrest from your instrument any sound or emotion you can imagine. You don't have to play all the notes, sometimes one or two are enough. But it helps to know where they all are.