Why is C major home base?

Why is it that the major key with no sharps or flats is called C and not A. Shouldn't 'C major' be written with three flats. A minor third above 'A major' with no flats.

It's a historical accident. There's a good explanation in the "Cambridge History of Western Music Theory."

Thanks. Could you tell me what chapter to look in?

Chapter 5. It's about middle ages theory.

Also, look up the term gamut and the guy, Guido.

Care to give a brief synopsis for those without access to the book?
Or perhaps an online link?
I do know something about Guido D'Arezzo (and there's plenty on him online),and about medieval modal theory.
I also know that the major key is a relatively recent invention, well after the time when letters were assigned to notes.

Given that we know Ionian was a late addition to the medieval set of modes (before going on to become our "major key") - and that the note letters were assigned well before that date - the question (IMO) comes down to:

Why was the letter A assigned to that particular note? Why was that chosen as the first low limit? (By Guido's time, AFAIK - well before the official arrival of Ionian - the "gamut" went down to G - "gamma ut".)
My pet theory has always been that "A" was a good average low note for male voices (some men can go lower but most can get down to A comfortably). I do know, of course, that pitch measurements have changed over the centuries, but a low A (a 10th below middle C) has always been around that register.
Maybe more pertinently, A was also the low limit of Hypodorian mode, the lowest-ranging mode of the eight medieval modes:

The four "authentic" modes were Dorian (D E F G A B C D), Phrygian (E F G A B C D E), Lydian (F G A B C D E F) and Mixolydian (G A B C D E F G).
Each had a "plagal" variant which ranged down to a 4th below the "final".
So the lowest of these was Hypodorian (A B C D E F G A, with D as final).
Assuming letters were assigned after this modal system was established, it makes sense that the bottom note in general use would be called "A". And also that the step structure beyond there would fit the model we now use (half-steps between B-C and E-F).

I'd be happy if anyone can either correct me or add more (bearing in mind I've oversimplified everything here!).

I'll just add to JonR's post that his post points to the fact that the OP has made a false assumption:

C Major is not home base.

The reason C Major is home base is because we're all taught music in a "C-centric" system largely because C Major is the key with no sharps and flats, and thus easier for beginners to learn, as the notes fall on the staff without accidentals, and on instruments like piano, it's easy to "see" C Major since it's all white keys.

But as JonR points out, historically, this is not the case.

"keys" didn't come about until the 1600s. Before then, we used modes.

All the modes used only "the white keys"

As time went on, the 4 (8 with plagal versions) modes JonR mentions - Dorian, Phrygian, Lydian and Mixolydian gradually had accidentals added to form two other common modes (and their plagal variants) such that after a while, Glareanus described in his "Dodecachordon" 6 (12 with plagal) modes - the two new ones were Aeolian and Dorian.

What we then see is a transition from the original Ecclesiastical modes, to "the 12", to just the two "new" ones being predominant. Aeolian is what "becomes" minor, and Ionian is what "becomes" Major.

With the layout of the system, playing Ionioan (eventually Major) on C could be done without using accidentals, which probably caused some added interest to this "new" mode (and you must remember that after 1000 years of hearing Dorian, Phrygian, Lydian, and Mixolydian, that Ionian and Aeolian were probably "fresh" sounding at the time).

So to the OP, since the letter system had already evolved long before the concept of "Major" keys, A happened to end up falling on what we eventually called minor, and C on Major.

Again though, it's our C-Centric way of thinking that causes this often asked question to arise.

C Major is no better, or different, or whatever than any other key. It is not "home" or "the first" or anything like that. It just happens to have no accidentals, so it's easier to begin teaching with.

Unfortunately, it's become so misunderstood in our culture that it is "home", some people can't get away from that idea.

HTH,
Steve

Typo, steve! :-)

stevel Wrote:
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> As time went on, the 4 (8 with plagal versions)
> modes JonR mentions - Dorian, Phrygian, Lydian and
> Mixolydian gradually had accidentals added to form
> two other common modes (and their plagal variants)
> such that after a while, Glareanus described in
> his "Dodecachordon" 6 (12 with plagal) modes - the
> two new ones were Aeolian and Dorian.

Aeolian and Ionian! ;-)

He also added Locrian, to complete the list, but as a theoretical-only mode, not for practical use.

Oops, thanks for catching that!

Yes Ionian and Aeolian.

Did Glareanus add Locrian - I thought it was a bit later to "complete" the system?

Steve