Can chords found in parallel modes of the relative minor of a key (or relative major when in a minor key) be considered borrowed chords?

Question

In the key of C major, take the following progression:

C----Em----A----G7----C

I------iii------VI----V7-----I

In this progression, can the VI chord be analyzed as a borrowed chord from the major mode (parallel major) of the relative minor?

I arrived at this interpretation because:

1) The chord has no leading tone to G7, so can't be a dominant leading chromatic chord.

2) The preceding chord (iii) isn't the secondary dominant of the chord (V7/VI), nor does it tonicize it, so I don't see how it can be transient modulation or tonicization.

3) It isn't a full-blown modulation as it doesn't last long enough, no other chords from the key are heard, and no other notes from the would be key are heard, most notably the leading tone (G#).

The background to this is that I was listening to David Bowie's 'Space Oddity' (in C major). The A major chord during the middle eight guitar solo part (which I believe is a direct transient modulation) got me curious as to the above question.

Answer 1

You have to look at what you have and look at where you are going. Like you said, the A does not naturally exist in C major, however, I think it would be a stretch to say it borrowed from A major since there is such a big jump to the parallel major of the relative minor key especially since the Em doesn't make A seem like a temporary tonic and neither G7 nor Em are in the key of A major.

I look at it this way:

You are going from Em to A to G7. The iii chord is rarely used in major pieces so instead it is used to take you to the chord outside the key. You can look at these 3 chords as a temporary progression borrowed from D major with as Em is ii, A is V, and G is IV. The dominant 7th is not in the key of D and you can look at the progression is trying to take you away from the key of C major, but the G7 is pulling you back.

The formal analysis of this would be rather tricky. I can see someone calling the A a non-functioning secondary dominant and have the analysis look like this:

C  Em    A     G7
I  iii   V/ii  V7

I could also see the Em also being denoted as from the supertonic key as such:

C  Em      A     G7
I  ii/ii   V/ii  V7

If I were to write this down for myself though just for simplicity I would just ignore the function and just write this:

C  Em    A    G7
I  iii   VI   V7

Even though this ignores the function, it is pretty clear the submediant is raised.

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In general, a borrowed chord is typically only borrowed from a key/mode that contains the tonic of the key you are in. (I.E. C major's tonic is C, A minor has a C in it and is the relative minor, but A major does not). Saying A is a borrowed chord in the key of C major is not really likely and very odd at best.

Answer 2

I suppose it could, but why bother? iii (Eminor in this case) is far from uncommon in a song in C major. It could act as a different flavour of C^7, moving on to F. It could lead to Am, maybe directly, maybe via E major. It could do plenty of other things.

Do get away from this idea that a key has "permitted" chords. It makes life so complicated, having to invent a modulation or modal shift any time a chromatic chord occurs!