This may sound a little strange. A question that I have long been interested in is how people visualize harmony. I think of different lines taking their own routes from beginning to end, meeting each other, and crossing each other and finally resolving out. But it seems to me that there are a lot of people who think in broader terms, of chord progressions, and sing to fill in the empty spaces. I think the way you see it, or hear it changes the notes you sing. I just wondered how other people out there who sing harmonies thought about it. And why they think about the way they do.