The way I use modes is almost strictly for harmonizing. That's pretty much all the use I get from any scale, even simple major or minor. Since the foundation of all music is it's chord structure and that progression. As you built a chord progression for a song, next your going to want to harmonize something over the chords. This is where scales and modes come into play. Each chord has a different scale (sometimes many scales) that fits it. Take a simple major chord. The natural scale to use to harmonize over it is the major scale. Basically because it contains all the notes that are compatible (or sound pleasant) with the sound of a major chord. Then you match the root, C major chord = C major scale. Now when you first learn scales, you always play them from the root up and then back down. The simple concept is that your learning each degree that each note has to it's relative sound(tonality/root). So if you play the C major scale over the C major chord, you know that D is one sound in relationship to the chord and E is another. I think, the best way to look at a scale is it's relationship to a chord it supports.

Take a simple chord progression in the key of G major.
Cmajor / / / / Ddom/ / / / Gmajor

Now of course you could just use the G major scale over the entire chord progression. Which is not a bad idea. I think it's the best thing if you are playing a melody that repeats over and over during the chord progression. But if your actually going to harmonize over it, it may be better to break the chord progression up. Play a C major scale over the C major chord, etc. What you end up with is more compatible notes with each chord.

Now the same things applies with modes. Take the Lydian mode which is a great alternative to using just the simple Major scale. If you were to compare the sound of the lydian scale to anything, it would be the sound of a IV chord. Now going back to playing one melody over all the chords. If you were to play the G major scale over the C major chord, you would actually be playing the C lydian scale over the C major chord. When you did that, the relationship between chord and scale would end up being the tonality of the lydian scale. Simple concept, but it opens up another perspective. Alternative: Or you could play the C major scale over the C major chord, which is also very compatible as I stated before. Now what you will end up with is a different tonality. If each chord in a song was an item in a painting (artistic impression of the song). Each scale/mode would be the different colors you could choose to make that item.

I think the best way to learn modes is to practice them harmonizing over chords that support them. The difference between a lydian scale and ionian is just one note, but that one note will open up a new view and understanding on harmonizing over a simple major chord. All the same with all the other scales. Accidentals in music generally come from these concepts of harmonizing chords with different scales.

[Edited by noticingthemistake on 04-08-2003 at 11:11 PM]