Sunday, February 15, 2009

Today, while riding the train to a gig in Boston playing the banjo for Gershwin's Rhapsody in Blue, I was preparing for a class in fugue that I'll be teaching tomorrow. (There's a sentence you don't hear every day!) I was reading what Fux had to say about modal fugue subjects and decided to apply some of those principles to canon writing.

Essentially, Fux says to construct a subject that suits the mode at hand and no other based on the spacing of the half steps within that mode. Since the fugue imitates at the dominant (fifth), that must be considered as well.

Here are the modes with the half steps in bold:

Ionian: C D E F G A B C

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

Mixolydian: G A B C D E F G

Aeolian: A B C D E F G A

For today's canon, I used the lydian mode. I have chosen to make it a canon at the fifth so that I can relate what I do to Fux's fugal precepts as much as possible.

Because there is a half step below both the tonic and dominant in this mode, I've chosen to have the opening of the melody proceed down from the tonic in the dux and down from the dominant in the comes. This guarantees that the characteristic raised 4th of the lydian will be featured early in the piece.

(click on image to enlarge)