Diabelli Project 025 - Canon in G

The Diabelli Project is about offering my weekly flash-composition sketches freely to all. Like Antonio Diabelli's theme these sketches aren't great music. But perhaps (as in Diabelli's case) there's a Beethoven out there who can do great things with them.

This week it's just a very simple canon, sort of. If you look at the date, you'll see that I wrote this over a year ago, so I'm not 100% certain of my intentions. It seems to be in G major -- the key signature matches, and the opening bar outlines a G major chord. But there's no strong sense of motion towards the dominant, D major. Could this possibly be in D Mixolydian mode? (click on image to enlarge)

That's for you to decide. This is as far as I got, but you're welcome to finish it. Does it remain a two-part canon, or do more voices come in? Questions, questions. If you have any answers, please let me know!