This was taught to me by Richie Hart, who was taught it directly from George Benson, who picked it up from hanging with Wes and Coltrane. You need to know your harmonized major scale. In the key of C, this is I chord: C maj7. II chord: D-7. III chord: E-7. IV chord: Fmaj7, V chord:G7, VI chord: A-7. VII chord: B-7b5. Now each of those chords has a function, meaning what it does to the melody being playd over it. It is either stable,(a resting place) (Tonic). Or is creating unstability, or wanting to move to a stable place. (Dominant) Dominant areas want to move to tonic areas. Think of when you sing AHHHH-mennnnn in church. You can hear the first part is dominant, then it moves to the resting area, or tonic. Now you have the seven chords above. There are three tonic chords. The I (CMaj7) the III (E-7) and the VI chord (A-7). These chords act the same way. They are all resting places, they just create a kind of different color, but they all function the SAME. Now there are 4 chords left. These are all Dominant chords. This means they are looking to resolve, or move to a resting area. Theses chords are the II chord: Dmin7. IV chord:Fmaj7. V chord: G7. and VII chord B-7b5. Now you only have two groups of chords, and ecah chord in each group funtuions the SAME way. This is SOOOOOOOOOOO important!!!!!! You do NOT have to learn 7 modes, one for each chord! If you do that, in a progression like a simple I-VI-II-V, you will be trying to play 4 modes to make the changes. Ionian on the I chord, Aolean on the VI chord, Dorian on the II chord, Mixolydian on the V chord, then back to Ionian on the one chord. UGGHH! Now if you look above at out groupings, you will see that the I and VI chord are in the same group, and are both tonic chords. YES! No need to make any changes there! Treat them both the exact same way. Play all your C maj lines, over BOTH chords. Of course A minor7 arpeggios will work, as will Emin arpeggios. All are tonic right? Now those two chords just became one. Now you have a D-7 and a G7 chord coming up. This is changing functions and is no longer a resting place. Although you are still in the key of C, if you accentuate C Maj, A min or E min, it will sound wrong. You will be playing the correct notes, but they will not be functioning the right way. Guys, THIS is what sets apart the good players from the bad. The tasteful from the bland. Dare I say it? Most jazz players from most rock players. On the Dominant chords, you must accentuate the correct notes. This comes from outlining the dominant chords. They ALL work! Look at our grouping above. You have D-7, G7, F Maj7 and b-7 flat V. You can play as simple as just D dorian over both chords, or go wild and use all of those arpeggios. This will be accentuating the correct notes, and lead you nicely back into the tonic area. To make it as simple as possible....The I and VI chord play C maj, the II and V chord play D dorian. I will make up a progression here that is more advanced, using all VII diatonic chords. Say we have a progression like this. Bar 1: C maj7 for 4 beats. Bar2: E min7-A-7 for 2 beats each. Bar III: F maj7-D-7 for 2 beats a piece. BarIV: B-7b5-G7 for two beats a piece. Lets look at this and break it down by function. Bar I: C maj 7= Tonic. Play all your Cmaj stuff here. easy enough! Bar 2. Oh no, two chords! WAIT! They are also both tonic chords! That means...Play more Cmaj stuff here! Bar III..DARN..two more chords..but wait..they are BOTH dominant chords! I can group them together as well! Make it easy, Ill play just D dorian over both. Ok..bar IV..SOB, I KNEW it! That strange Bbmin7b5 chord. What the heck do I do know?? I have to think of that stupid B Locrean mode?? What does Tag say..hmmm.... AHHH!!!!!!!!! Its STILL a dominant area!! I dont have to cahnge at all!! Just keep playing D dorian! YEEEHAAA!!! This is not to bad!!! oh no, ANOTHER chord, just when I was really moving. I KNEW it wasnt this easy. That jerk Tag, I knew he was just a big mouth. Well, lets see..hmmm, no way....you have got to be kidding me?? Its dominant as well?? That means I can STILL just play D Dorian?? I DONT BELIEVE IT!!!!!!! (Repeat after me everyone)... TAG WAS RIGHT, TAG WAS RIGHT, TAG WAS RIGHT,!!!!!!!!!!!!!! LOL!!!!!!! Now this is breaking it down as easy as possible, but THIS is where you start. You need to learn bop lines, and pay STRICT attention to what they are being played over, and if it is a tonic or dominat area. You see, bop lines are not like rock licks. They accentuate the notes that spell out the background chords. I studied scale for YEARS, trying to learn jazz. I knew everyone inside and out, upside down, in thirds, 4ths, triplets, 16th notes, and I still could not play a thing over changes. I got a new teacher, forgot about all the scales, started learning bop lines and songs, and within a year I was playing pretty darn well. As you advance, I can show you how easy it is to just apply the same thinking over almost any progression. Then as you get better, you can start adding little things like whole tone lines, and diminished lines (both of which fall into the same groupings above, I just did not go that far.) All the substitutions, Melodic and harmonic minor etc. It all fits together SOO easily. The hard part is trying to develope your own identity with it, but using this method, I think ANYONE can learn to be a very tasteful guitarist in a very short time. You HAVE to learn bop lines and standard songs. Start EASY. Polka dots and moonbeams. Stormy weather. JazzBlues tunes with changes. Keep it SIMPLE. If you start with Giat steps, Stella etc, you are in for frustration. Start easy, get a grasp of one thing, then add another. But LEARN THOSE BOP LINES!!!!!!!!!