Well, I guess it isn’t on the guitar, but at least on keyboard instruments, the key of C major is the one without any black notes in the scale. Why is that? I guess it makes more sense for C to be A. Do corresponds to C in the do-re-mi system, and it’s at the beginning, and it seems strange to me why they went with C in this case. Does anyone know how exactly that came to be?
Just to clarify, I understand why C is the basic key for the piano, but I am unsure why that key is given the name C instead of A, which seems more appropriate.
I don’t know the historical answer but I wouldn’t want the “base” key to signified as “A” because that would mean the relative minor scale would be F#/Gb minor which would mean a bunch of sharps/flats that are white keys instead of black.
I guess we could have theoretically laid out the key labels so that both the “A” and the “F” would have no accidentals but then that hypothetical scenario would be independent of any consequences of piano or guitar. (A label is just a label after all.)
Also, the A Major to relative F minor might be a little weird since you’re mentally crossing a boundary (G) backwards.
Reading here (and a few other places), it seems that in the dark ages and early middle ages various systems were used to name notes and scales. Eventually the early versions of the modal scales came into practice as well as a way of naming the notes in them.
So, at this point ABCDEFG was the choice for the Aeolian mode. As good as any I guess.
When Guido (see link above) gave us singing notes (Ut, Re, Mi, Fa…) he used a hymn that was firmly based upon the Ionian Mode: CDEFGAB
Our modern Major/Minor scales are a simplification of the modal scales. Modal scales could be seen as 3 general types: those that started with Tone, Semitone (this became minor) and those that started with Tone, Tone (this is major) and those that started with Semitone, Tone (ugly and ignored).
So, the Ionian was already in place starting on C before the major scale was derived.
The issue in thinking that the Major scale is the basic scale. It isn’t. The relative minor to C is A. Thus the A minor scale also has no sharps or flats. The piano thus is laid out with A minor as its basic key.
The different question is how musical scores came to use C as the central note between staves. That might give the impression that C was the “base” key, or had some other importance.
Just to clarify, the system of tones or semitones between the noteswould not change, but rather just the names of the notes. So, the relative minor to the new key of A would just be F. (Lower the name of the note by 2, and then start over if you hit the boundary.)
This isn’t always true. In French for example, they don’t use letters for the names of the notes, but do, re, mi and so forth, so Beethoven’s Ninth Symphony in D minor is La symphonie n° 9 en ré mineur.
A simple answer would be that the major scale came out after the notes were named. There was a primitive version of the major scale, but, at the time, it was forgotten.
The Ionian mode mentioned above is a fairly new concept, and postdates the invention of note letter names by centuries. The Lydian mode originally corresponded to the modern major scale, but this wound up being mistranslated from the Greek by the Church, and they wound up with a scale based on F. (but see below).
While Ut queant laxis starts on what we now consider do, it is in the Dorian mode, (Greek Phrygian) because the tonal center and final note is on “re.” That song did not create the major scale at all.
Unfortunately I can’t find an exact date online for the first use of the actual major scale, but I know it is not considered a feature of Medieval music, so I’m guessing late Medieval, early Renaissance. The proper Ionian mode didn’t pop up until 1547, created by Heinrich Glarean, but even he admits that the actual use of a major scale predates that, saying it was the most common mode.
One curious thing, the Lydian mode of the Church was more often realized as an F major scale: the B was flatted more often than left natural. This means that, despite what I said at the top, there was a major scale, just not a diatonic major scale, thus making it “improper.”
Whether this altered Lydian led to the use of the pre-Ionian, I have no idea. But it definitely would not explain the use of C as the starting note rather than F.
I hope none of that was confusing. It’s not my best written response.