Or to work out 7 of the most used modes instead of memorizing them, You just memorize this string:     T T S T T T S         where T stands for Tone, that is you skip a fret,( i.e. from 0 to 2), and S for Semitone, which is code for the very next fret (i.e. 0 to 1). If you find home, wherever you want it to be and use those intervals to construct a scale, you get the pirate mode. To construct the other 6 modes I mentioned, here's what you do:
   1 ) Remove the first letter
   2 ) Append it to the end... that's it.

So you get this pattern:

T T S T T T S     - Pirate mode, Major (happy sounding)
T S T T T S T     - This one sounds a little irish-ey to me, melancholic sounding. This is the one Guthrie is playing.
S T T T S T T     - This one sounds like flamenco or arabic. weird sounding.
T T T S T T S     - The Simpsons theme lives here.
T T S T T S T     - This is the same as the Pirate mode, except it has a dominant 7 (sounds bluesy)
T S T T S T T     - This one is your plain old vanilla "minor" scale.
S T T S T T T     - This one is the weirdest. give it a try.


Choose one, find it everywhere in your instrument, and you'll start finding hidden patterns like the one Guthrie showed, some scales coincide in different tonal centres. Now it's up to you to drone it, feel it, play it and really internalise them.