Why is the key without black keys called "C Major" & not "A Major" for alphabetical hierarchy?

I appreciated the kind answers when I asked before, but it seemed most answerers misunderstood my question, maybe because my wording was bad, so I'm rewording it. I know C major has no sharps or flats %26amp; is easiest to play, that middle C is 256 Hz, that there must be a standard for instruments to tune to, that many things are just arbitrary %26amp; that harmonic, melodic %26amp; natural minor scales differ. What I don't know is how C major historically ended up being the key with no black keys. I seem to recall modern major %26amp; minor modes were once the ionion %26amp; aeolian modes, respectively, of the old church modal system. I wonder if the ionion mode just happened to start on C before it became the most important mode. If so, I could see how the C major scale would be what remains after the other modes went out of use (just a guess, though). But that still wouldn't explain why C major has no black keys, especially since keyboards were developed after the primarily vocal modal medieval period.

Why is the key without black keys called "C Major" %26amp; not "A Major" for alphabetical hierarchy?
You've been teasing away at answering your own question, but just not making the last step. It's 35 years since I was up to my elbows in modal theory, so I crave pardon should I unwillingly skid into the long grass, but here's a potted version of the likely course of events between 400 and 500 years ago.





Though the Greek and subsequently the Gregorian and Mediaeval modal classification stand as a parent to child relationship with each other in many ways, they are not identical. Rather they overlap in the sense that you can map the Greek mode on to the Mediaeval in this manner: Greek Dorian equates to Mediaeval Phrygian. Bear this mapping in mind for a moment.





Though current harmonic thinking is completely key centric now, its origins are just as modal as the Greek and Mediaeval ones: like those, the major and minor modes can be constructed on any tone as long as their 'formula' is correctly maintained. I won't go through the scale constructions in detail that derive from the major and minor modes: any musical dictionary will give you those; we need to concentrate on just one of these in a moment.





By 1600, let's say, modal harmony in the form of major and minor modes are properly established, and they then begin to erode the use of the Church modes to the point, eventually, that they are effectively obliterated in practical terms.





Three scale constructions are derived from minor mode: natural minor, harmonic minor and melodic minor. Of these, our interest should be focused on natural minor.





Wizzened, dyed-in-the-wool modal harmonists were quick to notice that when constructing a natural minor scale on 'A', you actually got none other than an old modal friend, both Greek and Mediaeval Hypodorian which, with the introduction of the six later, transposed modes like Locrian, had acquired the designation (IX) Aeolian, with an ambitus of a-a' and a finalis of 'a' that made it distinct from the plagal Hypodorian. (It is the distinction of Aeolian's finalis being 'a' that is the critical point in this tale.)





Glory be: what better reason could there be to start one's exploration of these newfangled major and minor modes, and constructing their scales, if you could do it from a departure point that fully and respectably stood with not one, but both feet in both camps!





Realisation quickly dawned subsequently, that when you constructed a major mode scale on a tonus a minor third up from 'A' you required just as many accidentals as for 'A' Aeolian, i.e. none. And the principle turned out to apply throughout: any major mode scale constructed a third up from a natural minor (i.e. Aeolian) one, required the exact same number of accidentals to be applied. The relative key concept was born.





Given its role as a de facto bridgehead between the two tonal systems -- in effect it opened up the possibility of 'enharmonic modulation' between two entire tonal systems -- what more natural thing to do than to place 'A' Aeolian / 'a' natural minor at the root of your systematic construct and then count the seven diatonic tones upward as being 'A' to 'G' for your major/minor mode scale constructions..? That's precisely what was done.





So, not only do black keys, white keys, accidentals and key signatures (never mind 'middle C', which even pianistically is not in the middle at all) have nothing really to do with the origins of the nomenclature -- they are merely incidental by-products and reflections of it, instead -- they totally obscure the historical perspective too.





Thank the Aeolian / Hypodorian mapping capability instead... :-)
Reply:Yes, when the ionian mode was "invented" (Heinrich Glarean's "Dodecachordon" treatise of 1547) it was the C-C mode. He also added the aeolian mode (A-A), as well as the plagal range versions of both these modes (hypoionian and hypoaeolian). Prior to that, theorists only really recognized eight modes (dorian, phyrigian, lydian, mixolydian, and their plagals), but Glarean realized that this system was incomplete, so he completed it...and yes, he left out the B-B mode.





I'm sure the pitch wasn't fixed exactly at that time...or at least, not in the same way we think of it today. By that I mean that Glarean's C-C was not likely the same as the C-C you play on a modern piano. And it might not have even been the same each time he played/sang it.





But, since all the church modes involve only "natural" notes (at least, in their normal state...of course, we raise and lower notes...musica ficta and that whole bit), that seems to explain why the mode from C-C has no black keys. Now, when did Ionian "become" major? I don't know that. But it's important to remember that the Lydian mode, in practice, very often contained a natural (not raised) scale degree 4 -- Bb in the key of F "Lydian." Composers/theorists would have likely still thought of a piece using the notes F-G-A-Bb-C-D-E-F as being in F lydian, because of the final on F. But Glarean's modal system allows for a distinction to be made, and we can call that a transposed Ionian mode. If the pattern of whole and half steps that defines the Ionian mode was also what was frequently used in Lydian (and I suspect Mixolydian would have often had a raised 7th...otherwise there's no leading tone for a cadence), then eventually the distinction between the three modes becomes academic.





Aeolian is not as easy to understand...I'm not sure I really understand it. But remember that a LOT of pieces through the baroque era use "dorian" key signatures. (like a violin sonata in g minor that would have a key signature with one flat)





You might be interested in looking at a book by Joel Lester called "Between Modes and Keys." He's a brilliant scholar, and will do a much better job of explaining this than my sloppy attempt here.





And for the record, harmonic, natural and melodic minor scales are best thought of as variations on ONE scale, rather than three separate scales. You'll be really hard pressed to find a piece "in A harmonic minor" -- composers vary the qualities of scale degrees 6 and 7 ALL the time.





I don't know if any of this helps...it's too early in the morning for me to think straight.
Reply:oh please














Lord help us all.
Reply:My guess it it's like 'home row' on a computer keyboard. Sorry, that's the best I can up with.
Reply:I have both undergrad an grad degrees in music theory. Edik's answer is comprehensive, but let's back up several steps. You are making a primitive string instrument. You tune strings in fifths - you cannot get gut strings to reach the octave, and fifths sound like the *next best thing* to you. Let's say you start with a note we are gonna call 1. Nest tuned note is 5. If you move five up ( or invert it - those gut strings cant take much pressure!), you get the sound of 2. Got up 5 from that - you get 6. You start experimenting with resonances. 2+6 - the 1+5. There is no 3,4, or 7. The resonances you get, were you to sing a melody over them, would MOST LIKELY (not gonna go into WHY - not enough MEGS space ont his list!) imply a mode - either what became Aeolin, or you could argue for Dorian (you could also argue for others, but the argument is less convincing to ANCIENT ears). This shifts your universe - the note you were calling 2 NOW becomes your center. You base your new melodies on that sound - you are in a mode.





Times passes. You (your descendants??) extend the ideas. You add more notes. You find that PLAGAL leading tones (descending half steps) fall into place for you - sooner than you discover authentic LT. You move into TONAL music. You are in the dichotomy between modes are tonality. Modes - you are staring on A. Tonal - the relationship starts on C. This is how you reconcile them. WHEW!!! Not so much thought, as experience, codified in a primitive manner that matches you outlook about religions, planetary motion, and various other ideas of the day.
Reply:Nope. A major still has three black keys. C, F and G. Besides, C (major) is the key from all key. Like the purist or something. The leading key.