Mitch Friedfeld asks:

>Discussing the Antico, Brendan Carroll says that the first movement
>is based on the Mixolydian mode, and the slow movement derives from the
>Phrygian mode.  I've heard these terms before but way off in pre-history.
>What exactly is a mode?  And how does a Mixolydian differ from a Phrygian?

Briefly, the idea is this.  Imagine the white keys on the piano from C
to the C an octave above.  This is our major scale.  It's also the Ionian
mode.  Now imagine a scale running from D to the D an octave above.  This
is the Dorian mode.  There are consequently seven primary modes.  They
are:

C to c -- Ionian
D to d -- Dorian
E to e -- Phrygian
F to f -- Lydian
G to g -- Mixolydian
A to a -- Aeolian
B to b -- Lochrian

The last was rarely used, if at all.  It was more a theoretical construct.
Notice that each one of these modes has its own distinctive sound.  Also
notice that you can make a complete set of modes with any note as the
"home" tone.  That is, the Ionian mode can start on any tone.  The scale
Eb to eb -- Eb F G Ab Bb C D eb -- is the Ionian mode beginning on Eb,
the Dorian on Eb is Eb F Gb Ab Bb C Db eb, and so on.

Western music used to be based on modes until around the beginning of
the 17th century, when composers like Monteverdi switched from a modal
system to a harmonic one.  It's a technical, though consequential
difference.  "Modern" music -- music since Monteverdi -- tends to change
keys.  We speak of a modulation (unfortunate term, in this context) or
harmonic move from the key of C to, say, the key of G.  Music before
the Big Switch stayed in the same key, but moved among different modes
of that key.  Many Renaissance pieces will switch between Dorian and
Mixolydian, for example, in order to provide a sense of motion and
contrast.

These days, hardly anyone writes strictly within modes, except as an
exercise.  Even someone like Vaughan Williams (known for his love of the
modes) will mix modal writing with chromatic writing.  I haven't heard
the Marx quartets (although I have heard gorgeous songs), but I'd hazard
a bet that he mixes.

Steve Schwartz