first of all, I am not really Pochacco. I am his wife, and purely by chance I am a music history professor who specializes in medieval music. I’ve also done work on modern interpretations of medieval music – I’ll be teaching a class at UCLA this next quarter called Getting Medieval: medievalism in music and popular culture. So you can understand why my husband read your question and ran out to the living room to get me!
What you’re hearing in Greensleeves and other old tunes, and in newer music based on old tunes, are scales based on patterns that are different from the more modern major and minor ones. We call the older patterns “modes” (actually, we call "major’ and “minor” modes as well). Mode means “manner” and here it refers to the manner of arranging whole tones and half tones into a scale. In a major scale (think of C major – all the white keys on a piano starting on middle C) there are 5 whole tones and two half tones. The half tones (sometimes called half steps) are between E and F and B and C. If you can look at a piano keyboard (or imagine one) you’ll see that there are no black keys between E and F or between B and C. The pattern of intervals for a major scale is TTSTTTS (where T=tone and S=semitone. That’s the British way of saying half-step, and they invented this explanation in English).
[For the pattern of a minor scale, start on A and use all the white keys. The pattern that results is TSTTSTTT. The first two intervals – TT for the major, TS for the minor, give these modes their names. The major mode has a major, or bigger, third while the minor mode has a minor, or smaller, one – three semitones to the major third’s four.]
Major and minor modes begin to be used in music around the 16th century, and they really come into their own in the 17th century, with the invention of tonality. Before then, western music was based on different scales, the so-called Church Modes. They’re called church modes because the first theorists to write about them were church musicians concerned with understanding how gregorian chant worked. There are still only two half steps in the scales, but if you start your scale on different pitches, the half steps will turn up in different places in the scale. There were four places to start, if you imagine the white keys on the piano again: D, E, F and G. There is a LOT more I can tell you about modes but I won’t, for reasons of time. If you want to know more, just ask!
SO tunes written using these older scales will sound like music to us – they’re not from Mars, and they use all the same intervals we use today, just arranged differently. So they sound both familar and wierd at the same time. Let’s take Greensleeves, a 15th century English song. It uses the modal scale based on D (try it out), which 16th century theorists called the Dorian mode (another long story). D E F G A B C D are the pitches, and the pattern of steps is T S T T T S T. This mode begins with a minor third (D-F) and the tune Greensleeves begins with just this interval. Now a modern listener will hear this and on some level identify the sound as minor mode. But then the melody ascends by step and freaks us out: D F G A B A G E C. It starts out minor, but then sounds major. To be minor we should use B-flat instead of B so the semitone is between A and B-flat instead of between B and C. To us moderns this mode sounds like a bizarre combination of major and minor that catches the ear delightfully. It’s archaic but totally comprehensible as well.
So your observation is true: all medieval (and renaissance) music sounds like Greensleeves, if by that you mean that it uses modes that are different from our more modern major and minor.
